PROCESS AND SYSTEM FOR THE ALKYLATION OF AROMATIC COMPOUNDS

Abstract: This invention is directed to a reactive distillation process and system for the alkylation of liquid aromatic compounds with a liquid olefin or olefin/paraffin mixture. The aromatic compound may have from about 6 to about 30 carbons and the olefin may have from about 8 to 30 carbons. The system has a reactor configuration utilizing an alkylation catalyst, a reboiler with product takeoff, and a feed inlet above the catalyst bed. The system may also include a means for in-situ mixing of the aromatic compound and olefin or olefin/paraffin mixture, an overhead condenser and/or a water takeoff.

Description: PROCESS AND SYSTEM FOR THE ALKYLATION OF AROMATIC COMPOUNDS Technical Field This invention generally relates to a reactive distillation process and system for the alkylation of aromatic compounds with olefins Background Art Alkylated aromatics, including linear alkyl benzenes (LAB's) having long chains (typically 10-14 carbons), are commonly used, commercial products LAB's are commonly sulfonated to thereby produce surfactants. Typically, alkylated aromatics are manufactured commercially using classic Fnedal-Crafts chemistry, employing catalysts such as aluminum chlonde, or using strong acid catalysts such as hydrogen fluonde, for example, to alkylate benzene with olefins. While such methods produce high conversions, the selectivity to the 2- phenyl isomer is low, generally being about 30% or less. LAB's with a high percentage of the 2-phenyl isomer are highly desired because such compounds when sulfonated have long "tails" which provide enhanced solubility and detergent properties Reactive distillation methods for producing short chain alkylated aromatics are known These methods are typically directed toward reacting gaseous phase short chain olefins, such as ethylene or propylene, with benzene. Summary of the Invention It has now been recognized that alkylation reactions using long chain olefins present peculiar problems With longer chain liquid olefin reactants, lower space velocities may be necessary due to the low mutual solubilities of the feed components. Due to lower reaction temperatures, alkylation reactions involving long chain olefins may be prone to the accumulation of water brought into the alkylation unit with the feeds or formed as a by-product in the catalyst bed, leading to deactivation of the catalyst. Furthermore, because liquid olefins mix much less readily with liquid aromatics than do gaseous olefins, different mixing procedures are necessary in order to achieve high yields of desired LAB's. In addition, the use of longer chain liquid olefin reactants may lead to a greater tendency for the formation of carbonaceous deposits and heavy organics on the catalyst bed The formation of carbonaceous deposits and heavy organics on the catalyst bed By-product formation may generally be more difficult to control with the higher molecular weight olefin coreactants Therefore, a need exists for a method of alkylation of aromatics with long chain olefins that has high olefin conversion, high selectivity and having long catalyst lifetimes. In particular, a need exists for a method of producing alkylated aromatics from liquid mdustnal reactant feeds containing water that avoids water deactivation of the catalyst and which ensures adequate mixing of the liquid aromatic and olefin reactants. A need also exists for such a method having high substrate olefin conversion and long catalyst lifetimes. More particularly, a need exists for a method of LAB production having high substrate olefin conversion, high selectivity to 2-phenyl isomer LAB, and employing a catalyst having long lifetimes and easy handling. LAB is useful as starting mateπal to produce sulfonated LAB, which itself is useful as a surfactant. This invention provides a solution to one or more of the problems and disadvantages descnbed above. This invention, in one broad respect, is a process useful for prepanng alkylated aromatic compounds comprising introducing an aromatic compound having from about 6 to about 30 carbons and an olefin having from about 8 to about 30 carbons above a catalyst bed containing an alkylation catalyst under conditions such that the olefin and the aromatic compound react to form an alkylated aromatic compound; allowing the alkylated aromatic compound and unreacted aromatic compound to descend into a reboiler from the catalyst bed; withdrawing the alkylated aromatic compound from the reboiler; and heating contents of the reboiler such that the aromatic compound refluxes to contact the catalyst bed In a second broad respect, this invention is a system for manufactunng alkylated aromatic compounds, comprising a reactor containing an alkylation catalyst bed; one or more injectors in the reactor for introducing aromatic compound, olefin or a mixture of aromatic compound and olefin above the catalyst bed; a reboiler for collecting, heating and refluxing unreacted aromatic compound descending from the reactor, the reboiler positioned below and m communication with the reactor, the reactor and reboiler being generally m vertical alignment; and a means for withdrawing alkylated aromatic compound from the reboiler. Use of the process and system of this invention for alkylation of aromatics with long chain olefins, particularly alpha-olefins, or long chain olefin/paraffin mixed feed stocks advantageously achieves high conversion rates and long catalyst lifetimes by usmg the reactor configuration specified above. When the process and system of this invention is used for selective benzene monoalkylation by liquid olefin or liquid olefin/paraffin mixed feed stocks, high selectivity to 2-phenyl product isomers is advantageously obtamed. Additional benefits may be deπved from the process and system of this invention by utilizing a column of solid acid catalyst and a water condenser with water take-off above the catalyst bed as depicted, for instance, in FIG 1 and FIG. 2. A process operated in accordance with the representative apparatus of this invention depicted in FIG. 1 and FIG. 2 has the advantage that nsing benzene vapor from the reboiler continuously cleans the catalyst of heavy organics to thereby increase lifetime of the catalyst. Improved catalyst life and performance dunng benzene alkylation is enhanced by continuous water removal from the catalyst bed (without the need for a predrying step) and by better mixing of the reactants and increased effective benzene concentration in the alkylation reaction zone. In addition, when used for selective benzene monoalkylation this invention advantageously produces only low amounts of dialkylated benzene, which is not particularly as useful for detergent manufacture, as well as only low amounts of tetralin derivatives. Certain terms and phrases have the following meanings as used herein. "Meq/g" means milliequivalents of titratable acid per gram of catalyst, which is a unit used to describe acidity of the catalysts. Acidity is generally determined by titration with a base, as by adding excessive base, such as sodium hydroxide, to the catalyst and then back titrating the catalyst. "Conv." and "Conversion" mean the mole percentage of a given reactant converted to product. Generally, olefin conversion is about 95 percent or more in the practice of this invention. "Sel." and "Selectivity" mean the mole percentage of a particular component in the product. Generally, selectivity to the 2-phenyl isomer is about 70 or more in the practice of this invention. Brief Description of the Drawings FIG. 1 shows a representation of a first continuous reactive distillation column employed in the practice of this invention. FIG. 2 shows a representation of a second continuous reactive distillation column employed in the practice of this invention. Detailed Description of the Invention Catalysts Catalysts that may be employed in the practice of this invention include any solid acid alkylation catalyst. Representative examples of such solid catalysts include acidic zeolitic materials such as acidic Y zeolites, beta zeolites, acidic mordenites, acidic clays (particularly acidic montmorillonite clays), fluorided montmorillonite clays, fluorided beta zeolites, fluorided mordenites and silica-alumina combinations among others. Other catalysts that may be employed in the practice of this invention include those comprising a heteropoly acid, mineral acid, or phosphoric acid in combination with zeolite or non-zeolite solid inorganic oxide supports, large pore crystalline molecular sieve and or ion exchange resin, as well as mineral acid and carboxylic acid treated zeolites, such as mordenites. Acidic zeolites that may be employed in the process and system of this invention include both naturally occurring and synthetic silica-alumina zeolites. Acceptable acidic zeolites are characterized as being preferably dealuminized or as having a reduced alkali metal content and include those based on A, X, Y, and L type zeolites, eπonite, omega, beta, and mordenite. Other acceptable acidic molecular sieve catalysts include any of the various types of mole sieves having reduced alkali metal content. Preferred acidic zeolites for this invention are beta zeolite and dealuminated mordenite. The non-zeo tic solid inorganic oxide that may be employed with a Bronsted or Lewis acid in the process and system of this invention may be selected from among the inorganic oxides including alumina, silica, bona, titanium dioxide, zirconium dioxide, chromia, zinc oxide, magnesia, calcium oxide, silica-alumina, si ca- magnesia, si ca-alumina-magnesia, sihca-alumina-zirconia, chromia-alumma, alumina-bona, sihca-zirconia, etc and the various naturally occurring inorganic oxides of vanous states of purity such as bauxite, clay, diatomaceous earth, etc. The preferred inorganic oxide is a solid acid montmonllonite catalyst, particularly an acidic fluorided montmorillonite clay. The large and medium pore crystalline zeolites that may be employed with a Bronsted or Lewis acid in the process and system or this invention include zeolites such as ZSM-5, ZSM-12, ZSM-18, ZSM-20, zeolite Beta, zeolite L, mordenite, faujasite, zeolite Y, zeolite X and the rare earth metal-containing forms of the above. Other large pore ordered structures which can be used with a Bronsted or Lewis acid in the present invention include pillared silicates and or clays, aluminophosphates, e.g ALPO-5, VPI-5; sihcoaluminophosphates, e.g. SAPO-5, SAPO-37, SAPO-31, SAPO-40, SAPO-41; as well as other metal aluminophosphates. The ion exchange resins that may be employed in the process and system of the present invention include those macroreticular acid ion exchange resins having sulfonic acid groups, e.g., the sulfonated styrene- divinylbenzene copolymer exchange resins such as those commercially available as Amberlyst-15, Amberiyst XN-1005, Amberiyst XN-1010, Amberiyst XN-1011, Amberiyst XN-1008 and Amberhte 200. Microreticular acid ion exchange resins, such as Amberhte IR-120H may also be acceptable in the practice of this invention. Catalyst Preparation One preferred catalyst of this invention is a fluonne-containing mordenite Mordenite is a type of zeolite. This catalyst is prepared from acidic mordenite (typically having 0 1 percent or less of sodium) having a si ca- alumina molar ratio of from about 10:1 to about 100.1 More typically, the starting mordenite has a silica/alumina molar ratio of from about 10:1 to about 50:1 The starting hydrogen mordenite, which is commonly available commercially, is treated with an aqueous solution of hydrogen fluoride ("HF") to produce the active, long-life and highly selective catalyst of the invention. In the course of such HF treatment, as well as dunng subsequent calcmation of said HF-treated mordenite, the silica/alumina molar ratio typically increases. The finished catalysts of this invention show a fluorine content of from about 0.1 to about 4 percent by weight, more typically about 1 percent. While not wishing to be bound by theory, it is believed that the HF reacts with sites where -Si-O-Al- linkages occur such that the linkage is broken with fluonne becoming bonded to the Al such that -Si-OH and F- Al- groups form. This is believed to decrease the total Bronsted acid sites and mcrease the strength of the remaining acid sites in the mordenite and is believed to stabilize the acidity of the mordemte such that the mechanisms which degrade performance dunng LAB production, such as coke build-up, are retarded. The aqueous solution used to treat the mordenite may contain a range of HF concentrations. Generally, the HF concentration is a minimum of about 0.1 percent by weight. Below such minimum concentration, the effect of the fluoπne treatment sigmficantly decreases, resulting in the undesirable need for repeated treatments. Generally, the HF concentration on the upper end is about 10 percent by weight or less. Above a concentration of about 10 percent by weight, the HF is so concentrated that it is difficult to prevent HF from destroying the crystallinity of the mordemte, thereby detrimentally affecting its efficacy as a catalyst for LAB production The aqueous HF solution may be prepared by diluting commercially available 48% HF solutions to the desired concentration. Alternatively, HF can be sparged into water to provide an aqueous HF solution. Typically, the treatment is earned out by adding mordemte powder or pellets to a stirred aqueous HF solution at a temperature of from about 0 * C to about 50 " C. The stirπng and contacUng is continued for a time sufficient to achieve the desired level of fluonne m the mordemte. This time may vary depending on factors such as HF concentration, amount of HF solution relative to the amount of mordenite being treated, stirπng speed or speed of whatever agitation is employed, and temperature. After treatment, the mordemte can be recovered as by filtration, and then dπed. It is also possible to impregnate the mordenite to incipient wetness with a given HF solution, as well as to treat the mordenite with gaseous hydrogen fluoπde. Preferably said fluoπde-treated mordenite would be calcmed in air pπor to use in alkylation service. The preferred calcmation temperature would be in the range from about 400 ° C to about 600 " C Alternative mordenite fluoπnating agents to hydrofluoπc acid and hydrogen fluoπde include ammonium fluoπde, fluoπded silicon compounds and fluoπded hydrocarbons The HF-treated mordenite of this invention generally has about 0 1 percent by weight or more of fluoπne based on the total weight of the mordenite. Typically, the fluoπne-contaimng mordenite contains about 4 percent by weight or less fluoπne. The fluonne-containing mordenite most typically contains about 1 percent by weight of fluoπne. The mordemte can be used in the practice of this invention as a powder, in pellet form, as granules, or as extrudates. The mordemte can be formed into pellets or extrudates using binders well known to those of skill in the art, such as alumina, silica or mixtures thereof When used with mis invention, fluonne treated mordenite catalyst advantageously produces high selectivities to the 2-phenyl isomer in the preparation of LAB, generally producing selectivities of about 70 percent or more. Also, when used in the apparatus of this invention, the fluonne treated mordenite enjoys a long lifetime, preferably expenencing only a 25 percent or less decrease in activity after 400 hours on stream. Reactants for Production of Alkylated Aromatics In the practice of this invention, aromatic compounds are alkylated with olefins. These reactants can be handled and puπfied as is generally performed by those of skill in the art. In this regard, it is preferred that the reactants are water and alcohol free. The aromatics, which may contam one or more alkyl substituents, employed in the practice of this invention have a total number of carbons ranging from about 6 to about 30 carbons, preferably from about 6 to about 9 carbons. Representative examples of such aromatic reactants include benzene, toluene, cumene, decyl benzene, biphenyl, naphthalene, propyl benzene, xylene, ethyl toluene, diphenylmethane, styrene, diphenylethane, phenol, and benzyl halides. The olefins employed in the practice of this mvention have from about 8 to about 30 carbons, preferably from about 10 to about 14 carbons, such as is available commercially or produced as dehydrogenated paraffin feed stocks. It is preferred that the olefin be monounsaturated. It is most preferred that the olefin be an alpha-olefin containing a terminal ethylenic unit. Commonly, said olefins would be available in a paraffinic media of the same carbon range. Olefins m the 10 to 14 carbon number range would typically be available from C I0 to C, 4 paraffin dehydrogenation in a C, 0 to C, paraffin mixture having an olefin content of 5 to 20% Often, the olefin content of said olefm-paraffin mixture would be 8 to 10 weight %. An example of a compound produced using the process and system of the present invention for benzene monoalkylation is the 2-phenyl isomer of the LAB having the formula: wherein n is from about 5 to about 17 and preferably from about 7 to about 11. Process Conditions, Procedures, and Apparatus In a preferred embodiment, the process of this invention can be earned out to monoalkylate benzene usmg the continuous reactive distillation column depicted in FIG. 1. In FIG. 1, a feed mixture of benzene and olefin, generally at a benzene-to-olefin molar ratio range of about 1:1 to 100:1 flows from feed pump 10 to feed inlet 14 via line 12. The feed mixture falls to packed mordemte catalyst bed 32 where alkylation in the presence of the fluoπne-contaimng mordenite occurs. Alternatively, while not depicted in FIG. 1 , the benzene and olefin can be mtroduced separately into the bed with mixing occurring in the bed, or the reactants can be mixed via an in-line mixer pnor to introducing the reactants into the catalyst bed, or the reactants can be injected separately above the bed with mixing affected by use of standard packmg above die bed, or the reactants can be sparged mto the chamber above the bed Because of the lack of affinity between liquid aromatics and olefins, mixing of the liquid reactants is important to achieve good conversion. Therefore, to achieve good conversion when the reactants are injected separately it is especially important to provide for mixing within the reactor. The catalyst bed 32 depicted in FIG. 1 for laboratory scale may be made of two lengths of 1.1 inch (2 8 cm) internal diameter tubing, the lengths being 9.5 inches (24 1 cm) and 22 inches (55.9 cm). In the catalyst bed 32, the falling feed mixture also contacts nsing vapors of unreacted benzene which has been heated to reflux m reboiler 42 by heater 40 Such πsmg vapors pass over thermocouple 38 which monitors temperature to provide feedback to heater 40. The πsmg vapors of benzene and/or olefin also pass through standard packmg 36 (e.g , 7.5 inches (19 cm) of goodloe packmg). The nsing vapors heat thermocouple 30 which connects to bottoms temperature controller 28 which activates heater 40 when temperature drops below a set level. Acceptable catalyst distillation structures for use in the process and system of the present invention include stars, doughnuts and spheres. Prefeπed catalyst distillation structures are extrudates, tablets, and granules Pπor to startup, the system may be flushed with nitrogen which enters via line 54 and which flows through l e 58. After startup, a nitrogen blanket is ma tained over the system. Also pnor to startup and dunng nitrogen flush, it may be desirable to heat catalyst bed 32 so as to dπve off water from the fluonne-contaimng mordenite. Residual water from d e feed mixture or which otherwise enters the system is collected in water trap 24 upon bemg liquified at condenser 21 (along with benzene vapor). If the feed is very dry (free of water) the water trap 24 may not be needed. Removing water leads to longer catalyst lifetime Hence, the water trap 24 is optional. The same applies to FIG. 2. Condenser 21 is cooled via coolant such as water entering condenser 21 via port 22 and exiting via port 20. As needed, water in water trap 24 may be drained by opening dram valve 26. As needed, when LAB content in reboiler 42 πses to a desired level, the bottoms LAB product may be removed from the system via lme 47, using either gravity or bottoms pump 48 to withdraw the product. When product is so withdrawn, valve 44 is opened. In FIG. 1, dip tube 46, which is optional, is employed to slightly mcrease the pressure m reboiler 42 to thereby raise the boiling point of benzene a degree or two. Likewise, a pressure generator 56 may be optionally employed to raise the pressure of the system. Other standard pressure mcreasmg devices can be employed Pressure can thus be mcreased m the system such that the boiling point of benzene increases up to about 200 * C. In FIG. 1, control mechanisms for heat shutoff 50 and pump shutoff 52 are depicted which serve to shut off heat and pump if the liquids level in the system πses to such levels These control mechanisms are optional and may be included so that the catalyst bed does not come into contact with the bottoms of the reboiler. In the practice of this mvention in the alkylation of benzene, a wide vaπety of process conditions can be employed. In this regard, the temperature in the catalyst bed may vary depending on reactants, rate of introduction into the catalyst bed, size of the bed, and so forth. Generally, the bed is mamtained at the reflux temperature of benzene depending on pressure. Typically, the temperature of the catalyst bed is above about 70 " C, and most likely about 78 ° C or more, in order to have reasonable reaction rates, and about 200 ° C or less to avoid degradation of reactants and products and to avoid deactivahon of the catalyst as by coke build-up Preferably, d e temperature is in the range from about 80 * C to about 140 * C. The process may be operated at a vaπety of pressures dunng the contacting step, with pressures of about atmosphenc most typically be g employed. When the process is operated using a system as depicted in FIG 1 and FIG. 2, the reboiler temperature is maintained such that benzene and olefin vapoπze, the temperature varying depending on olefin, and generally being from about 80 * C to about 250 ' C for olefins having 10 to 14 carbons The composition of the reboiler will vary over tune, but is generally set initially to have a benzene to olefin ratio of about 5:1, with this ratio bemg maintained dunng the practice of this invention. The rate of introduction of feed mto the catalyst bed may vary, and is generally at a liquid hourly space velocity ("LHSV") of about 0.05 hr ' to about 10 hr ', more typically from about 0.05 hr '1 to about 1 hr '. The mole ratio of benzene to olefin mtroduced into the catalyst bed is generally from about 1:1 to about 100:1. In commercial benzene alkylation operations, it is common to run at mole ratios of from about 2:1 to about 20:1, which can suitably be employed in the practice of this invention, and to charge said olefins as an olefin-paraffin mixture compπsing 5% to 20% olefin content. Said olefin-paraffin (HC) mixtures are normally generated commercially through dehydrogenation of the corresponding paraffin starting mateπal over a noble metal catalyst Another preferred embodiment of the continuous reactive distillation apparatus is depicted in FIG. 2. In FIG. 2, the feed mixture enters the reactor via feed inlet 114. The feed mixture falls through the column to catalyst bed 132, wherein alkylation to form LAB occurs. A thermowell 133 monitors the temperature of said catalyst bed 132 The catalyst bed 132 may be optionally heated externally and is contained within 1-1/4 inch (3.2 cm) stainless steel tubing. Goodloe packing is positioned at packing 136 and 137. LAB product, as well as unreacted benzene and olefin, fall through packmg 136 into reboiler 142. In reboiler 142, electπc heater 140 heats the contents of reboiler 142 such that heated vapors of benzene and olefin πse from the reboiler 142 to at least reach catalyst bed 132. As needed, the bottoms LAB product may be removed from reboiler 142 by opemng bottoms valve 144 after pass g through lme 147 and filter 145. Residual water from the feed mixture, or which otherwise enters the system, may be condensed at condenser 121 which is cooled with coolant via inlet line 122 and exit lme 120. The condensed water falls to water trap 124, which can be dramed as needed by opemng dram valve 126. Temperature in the system is momtored via thermocouples 138, 130, and 165. The system includes pressure release valve 166. A nitrogen blanket over the system is maintained by introduction of nitrogen gas via inlet lme 154. Level control activator 150 activates bottoms level control valve 151 to open when the liquids level the reboiler nses to the level control activator 150. In this preferred embodiment, the catalyst distillation structure compnses extrudates, granules or tablets. While the systems depicted in FIG. 1 and FIG. 2 show single catalyst bed systems, it may be appreciated mat multi-catalyst bed reactors are within the scope of this invention, as well as multiple ports for mlet feeds, water traps, product removal lines, and so forth Moreover, the process may be run in batch mode, or in other continuous processes using plugflow designs, tπckle bed designs, and fluidized bed designs The following examples are illustrative of the present invention and are not intended to be construed as limiting the scope of the mvention or the claims. Unless otherwise indicated, all percentages are by weight. In the examples, all reactants were commercial grades and used as received. The apparatus depicted in FIG. 1 was employed for most of the following examples. The equipment of FIG. 2 was used in Examples 11, 12, 17 and comparative Example 2 It may be noted that Example 1 illustrates benzene alkylation with 1-decene usmg a solid acid, fluonded clay catalyst and the process design of FIG 1 compnsing a column of solid acid catalyst, a liquid reboiler fitted with product takeoff, water collection and takeoff, and a feed inlet above the catalyst bed. Typical data in Table 1 show greater than 95% 1-decene conversion per pass, 10-17% total decylbenzene product (∑Ph-C. 0 ) effluent concentrations, and 37-38% 2-phenyldecane (2-Ph-C 10 ) selectivities. Examples 2-8 illustrate benzene alkylation runs using similar technology, but where the production of total decylbenzene product, ∑Ph-C< 0 is shown as a function of changes in benzene/1 -decene feed rates (LHSV vaned from 04-1.0), feed composition (benzene/ 1 -decene molar ratio vaπed from 20 1 to 5.1), selected olefin (benzene/ 1-octene = 20: 1), reactor tube diameter (vaned from 1"-1 5/8") and catalyst life (200 hr) Example 9 shows the use of a solid acid zeolite (beta-zeolite) catalyst the same equipment and where 2-Ph-C 10 selectivity Example 10 illustrates alkylation of benzene using another solid acid zeolite (dealuminized mordemte) in the same unit and using a benzene plus olefin paraffin feed mix. Good catalyst life is realized with this mordemte Examples 11 and 12 demonstrate benzene alkylation with 1 -decene in a pressunzed version of the unit, shown in FIG. 2, usmg either acidic fluoπded clay or beta zeolite catalyst. Examples 13-21 illustrate LAB production usmg the process and system of the present invention with the preferred flouπde-treated mordenite catalyst In particular, Example 14 illustrates LAB production from paraffin dehydrogenate usmg the fluonde-treated mordenite catalyst of example B, where good catalyst life (250+ hrs) is achieved without catalyst regeneration, while mamtammg a 2-phenyl LAB selectivity of >70% and high LAB productivity without significant loss of fluoπde Comparative example 1, on the odier hand, usmg untreated mordenite, with no fluonde added, shows a rapid decline in LAB production. In addition, examples 15 and 16 illustrate LAB production using a 5:1 molar benzene/C |0 -C M olefin feed mix and the fluonde-treated mordemte catalysts of Example B when operating at different LHSV's in the range of 0.2-0.4 hr '. Example 16 shows 2- phenyl LAB selectivity of >70% coupled with high LAB productivity over a time penod greater than 400 hours Example 15 shows that catalyst life may exceed 500 hours without catalyst regeneration. Example 17 illustrates LAB production with the fluonde-treated mordenite catalyst where the alkylation is conducted at higher temperatures and under pressure. Examples 18-20 illustrate the performance of three HF-treated mordenite catalysts with different fluoπde loadings. Example 21 shows how virtually no alkylation activity is observed with a highly-fluoπnated mordenite. Comparative Example 2 shows the poor alkylation performance of the LAB production unit of Fig. 2 when the C.o-C. 4 paraffin dehydrogenate is injected separately from the benzene, at a pomt midway up the catalyst bed In mis comparative example, lower alkylate concentrations were obtained and higher concentration of heavies were observed Examples A and B illustrate the preparation of fluonde-treated mordenite catalyst. EXAMPLE 1 This example illustrates an improved, continuous benzene alkylation usmg a solid acid, fluoπded clay catalyst and die process design of FIG. 1. Benzene alkylation with 1 -decene was conducted using die process unit design of FIG. 1, attached. The process unit compπses the following pnncipal features: a column of solid acid catalyst, packing columns above and below the catalyst bed, a liquid reboiler fitted with a liquid bottoms product takeoff, a condenser fitted with water collection and takeoff, a feed inlet above the catalyst column and the necessary temperature and pressure controls. In this example, alkylation was conducted by first charging 100 ml of benzene/1 -decene (20:1 molar) mix to the reboiler and 250 cc of solid acid clay catalyst (0.5% HF on acidic montmoπllo te clay granules dπed in vacuum, 20/60 mesh) to the 1 " diameter reaction zone. The solid acid catalyst was held in place usmg Goodloe packmg The reboiler mixture was then heated to reflux and a benzene/ 1 -decene mixture (20:1 molar) was continuously mtroduced mto the unit above the catalyst column at the rate of 20 cc/hr (LHSV = 0 08) Under steady state conditions, liquid product was continuously withdrawn from the reboiler and water taken off from the water trap. The crude liquid product was peπodically analyzed by gas-liquid chromatography (hereinafter "GLC") Results are summanzed in Table 1 'Benzene/ 1 -decene (20 1) m reboiler brought to reflux b Shut down overnight Examples 2-8 These examples illustrate contmuous benzene alkylation usmg the same solid acid clay catalyst of Example 1 and the process design of FIG. 1, but with a vanety of process modificahons. Followmg the procedures of Example 1 and using the equipment of FIG. 1, alkylation of benzene was conducted as descnbed in Example 1 but with me followmg modifications' Example 2, The benzene/1 -decene feed rate was mcreased to 100 cc/hr (LHSV 0.4) -see Table 2, Example 3, The reaction zone inner diameter was mcreased to 1 5/8" (4.1 cm) - see Table 3, Example 4, The benzene/1 -decene feed rate was further increased to LHSV 1.0 - see Table 4. Example 5, The benzene/ 1 -decene feed molar ratio was lowered to 10:1 - see Table 5; Example 6, The benzene/1- decene feed molar ratio was further lowered to 5.1 - see Table 6; Example 7, 200 hr of solid acid clay catalyst life without significant loss of activity was demonstrated - see Table 7; and Example 8, Benzene alkylation with 1- octene was demonstrated - see Table 8 Table 2 - Example 2 Results (Benzene/1 -Decene Feed) "Reboiler liquid: product from run Example 1 b Shut down overnight c Stπpped product Example 2 Remarks: 250 cc of the catalyst from Example 1 was used: acidity = 0.45 meq/g; H 2 0 = 0.73% LHSV=0.4 Charactenstics of recovered catalyst: acidity = 0.47 meq/g; H 2 0 = 2.0% Table 3 - Example 3 Results (Benzene/1 -Decene Feed) "Reboiler liquid: product from Example 2 b Shut down overnight 'Stripped product Example 3 Remarks: 250 cc of me catalyst from Example 1 was set in a 1 5/8" (4.1 cm) diameter column LHSV=0.4 Characteristics of recovered catalyst: acidity = 0.44 meq/g; H 2 0 = 4.9% • Reboiler liquid product from run 7102-30 b Shut down overnight ■ "Stripped product 200 cc of the catalyst from Example I was set in a I 5/8" (4 1 cm) diameter column LHSV=1 0 Characteristics of the recovered catalyst acidity = 046 meq/g, H 2 0 = 3 8% "Shut down overnight b Stπpρed product Example 5 Remarks 250 cc of the catalyst from Example I was set in a 1 5/8" (4 1 cm) diameter column LHSV=04 Table 6 - Example 6 Results (Benzene/ 1 -Decene Feed) "Shut down over weekend b Stripped product Example 6 Remarks: 250 cc of the catalyst from Example 1 was set in a 1 5/8" (4.1 cm) diameter column LHSV=0.4 Table 7 - Example 7 Results (Benzene/ 1 -Decene Feed) "Stripped product Example 7 Remarks: 250 cc of die catalyst from Example 1 was set in a 1 5/8" (4.1 cm) diameter column LHSV=0.4 Table 8 - Example 8 Results (Benzene/ 1-Octene Feed) Example 8 Remarks: Catalyst from Example 7 was used Feed = 100 cc/hour (LHSV = 0.4) EXAMPLE 9 This example illustrates continuous benzene alkylation using a solid acid zeolite catalyst and me process design of FIG. 1. Followmg the procedures of Example 1 and using the equipment of FIG. 1 , alkylation of benzene was conducted as descnbed, but usmg 250 cc of solid acid zeolite catalyst (80% beta zeolite, 20% alumina bmder, 1/16" (0.16 cm) diameter extrudates). A benzene/1 -decene mixture (20.1 molar) was fed continuously at a rate of 100 cc/hr. Under steady state conditions, product effluent samples exhibited the following charactenstics ∑Ph-C, 0 concentration, 9 7%; 2-Ph-C, 0 selectivity, 50%; and ∑C< 0 concentration, 0.1%. EXAMPLE 1Q This example illustrates continuous benzene alkylation with a C, 0 -C u olefin paraffin mixture usmg a solid acid zeolite catalyst and the process design of FIG 1. Following the procedures of Example 1 and using the equipment of FIG. 1, alkylation of benzene wrth a C, 0 -C M olefin paraffin mixture was conducted as descnbed in Example 1, but usmg 250 cc of another solid acid zeolite catalyst (dealuminized mordenite, Sι0 2 /Al 2 0 3 (molar ratio 20:1), 1/16" diameter extrudates calcined at 538 'C and dned at 150 °C). A mixture of benzene and a C 10 - C, 4 olefin/paraffin mix (containing 8.5% olefin) was fed continuously at 100 cc/hr (LHSV = 0.4) The benzene/olefm molar ratio was 10:1. Under steady state conditions, the product effluent was sampled and analyzed by GLC over approximately 100 hours of operation. The results are summaπzed in Table 9. Table 9 - Example 10 Results (Benzene/C 10 -C H Olefin/Paraffin Feed) EXAMPLE U This example illustrates continuous benzene alkylation using a solid acid fluoπded clay catalyst and a pressure unit design of die type shown in FIG. 2. Benzene alkylation with 1 -decene was conducted using a process unit of the type shown in FIG. 2, constructed of 316 stamless steel. About 100 ml of benzene/ 1 -decene (20:1) molar mix was charged to the reboiler and 250 cc of solid acid catalyst (0.5% HF on acidic montmoπllonite clay granules, 20/60 mesh) was charged to the 1 1/4" (3.2 cm) id reaction zone. The reboiler liquid was then heated to reflux and a benzene/1- decene mixture (20:1 molar) conϋnuously introduced into the unit above die catalyst column at a rate of 100 cc/hr. Under steady state conditions, reaction conditions were maintamed as follows: Reboiler temperature, 132 * C; Reaction zone temperature range, 70-100 " C; and exit pressure, 4.1 psi. Liquid product was contmuously wi drawn from the reboiler and water taken from the water trap The crude liquid product was peπodically analyzed by GLC. Typical results were as follows: ∑Ph-C 10 concentration, 15.1%; 2-Ph-C, 0 selectivity, 37%; and ∑C. 0 concentration, <0.1%. EXAMPLE 12 This example illustrates continuous benzene alkylation usmg a solid acid zeolite catalyst and a pressure umt design of me type shown m FIG. 2. Benzene alkylation with 1 -decene was conducted using a process u t of the type shown in FIG. 2 Following the procedure of Example 11, 250 cc of solid acid zeolite catalyst (80% $-zeohte, Sι0 2 /Al 2 0 3 (molar ratio 23.9:1), 20% alumina bmder, 1/16" (0.16 cm) diameter extrudates) was charged to the 1 1/4" (3.2 cm) diameter reaction zone. The reboiler liquid was then heated to reflux and a benzene/ 1 -decene mixture (20 1 molar) contmuously introduced mto the unit above the catalyst column at a rate of 100 cc/hr. Under steady state conditions, reaction conditions were maintained as follows: Reboiler temperature, 171 " C; Reaction zone temperature range, 100-192 ° C; Exit pressure, 1.7 psi Liquid product was continuously withdrawn from die reboiler and water taken from die water trap. The crude liquid product was peπodically analyzed by GLC. Typical results were as follows- ∑ Ph-C, 0 concentration, 8.4%; 2-Ph-C, 0 selectivity, 47%, and ∑ C l0 concentration, 1.8%. EXAMPLE A This example illustrates die preparation of a hydrogen fluoπde-modified mordemte. To 30 g of acidified mordenite (LZM-8, Sι0 2 /Al 2 0 3 ratio 17; Na 2 0 wt% 0.02, surface area 517 m 2 /g, powder, from Union Carbide Corp.) was added 600 ml of 0.4% hydrofluoπc acid solution, at room temperature After 5 hours die solid zeolite was removed by filtration, washed wi distilled water, dned at 120 * C overnight, and calcmed at 538 " C. EXAMPLE B The example illustrates die preparation of a hydrogen fluoπde-modified mordemte. To 500 g of acidified, dealuminized, mordemte (CBV-20A from PQ Corp.; SiO^Al^ molar ratio 20; Na 2 0, 0.02 wt%, surface area 550 m 2 /g, 1/16" (0.16 cm) diameter extrudates, d at had been calcmed at 538 'C, overnight) was added a solution of 33 ml of 48% HF solution in 1633 ml of distilled water, die mix was cooled m ice, stirred on a rotary evaporator overnight, dien filtered to recover die extruded solids. The extrudates were further washed with distilled water, dned in vacuo at 100°C, and dien calcmed at 538 °C, overnight. Analyses of the treated mordenite showed: F, 1.2% and acidity, 0.49 meq/g. EXAMPLE 13 This example illustrates die preparation of linear alkyl benzenes usmg a hydrogen fluonde-modified mordemte catalyst. To a 500 ml flask, fitted widi condenser and Dean Stark Trap was added 100 ml of benzene (reagent grade) plus 10 g of hydrogen fluonde-modified mordenite zeolite, prepared by die method of Example A The mix was refluxed for 15-20 minutes to remove small amounts of moisture, then a combmation of benzene (50 ml) plus 1-dodecene (10 g) was injected into die flask and me solution allowed to reflux for 3 hours. Upon cooling, die modified mordemte catalyst was removed by filtration, die filtrate liquid flashed to remove unreacted benzene, and d e bottoms liquid analyzed by gas chromatography Typical analytical data are summanzed in Table 10 EXAMPLE 14 This example illustrates the preparation of linear alkylbenzenes from paraffin dehydrogenate using a hydrogen fluonde-treated mordemte catalyst. In the example, benzene was alkylated with a sample of C, 0 -C 14 paraffin dehydrogenate containing about 8.5% C l0 -C< 4 olefins. Alkylation was conducted in a process umt as shown in FIG. 1. Alkylation was conducted by first charging 500 ml of a benzene/paraffin dehydrogenate mix (10:1 molar ratio, benzene/C, 0 -C. 4 olefin) to the reboiler and 250 cc of the HF-treated mordenite of example B to die 1.1 " (2.8 cm) l.d. reaction zone. The mordemte was held in place using Goodloe packmg. The reboiler liquid was then heated to reflux and a benzene plus C 10 -C< 4 paraffin dehydrogenate mix (10.1 molar ratio, benzene/C< 0 - C 14 olefin) contmuously mtroduced mto me unit above me catalyst column at die rate of 100 cc/hr. (LHSV=04 hr '). Under steady state, reflux, conditions liquid product was contmuously wi drawn from die reboiler and water contmuously taken off from me water trap The crude liquid product was penodically analyzed by gas chromatography. The reboiler temperature was typically in die controlled range of 97-122 " EC. The column head temperature vanabihty was 78-83 ° C. A summary of the analytical results may be found m Table 11. After 253 hours on stream, the recovered HF-treated mordemte catalyst showed by analysis: F: 1.1% Acidity: 0.29 meq/g H,0: 0.3% Comparative Example 1 This example illustrates the preparation of linear alkyl benzene from paraffin dehydrogenate using an untreated mordenite catalyst. Following die procedures of Example 14, the alkylation unit was charged with 250 cc of untreated, calcined, mordenite, (d e starting mordenite of Example B), and the liquid feed comprised benzene plus Cj 0 -C, 4 paraffin dehydrogenate mix in a 10:1 molar ratio of benzene/C l0 -C, 4 olefin. Typical results are summarized in Table 12. The recovered mordenite showed by analysis: Acidity: 0.29 meq/g H 2 0: 2.1% EXAMPLE 15 This example also illustrates the preparation of linear alkyl benzene from paraffin dehydrogenate usmg a hydrogen fluonde-treated mordemte catalyst. Following me procedures of Example 14, die alkylation umt was charged wifli 250 cc of the HF-treated mordenite of Example B, and the liquid feed compπsed a benzene plus Cιo-C 1 paraffin dehydrogenate mix in a 5:1 molar ratio of benzene/C 10 -C, 4 olefin, the reboiler temperature was typically in die range of 122-188 "C, the column head temperature 78-83 ' C. Typical analytical results are summaπzed m Table 13. After 503 hours on stream, the recovered HF-treated mordenite catalyst showed on analysis: F, 1.0%; acidity, 0.35 meq/g; and H 2 0, 0.1% Table 13 - Example 15 Results (Benezene/C, 0 -C| 4 Olefin/Paraffin Feed) " Corrected for benzene in effluent sample. b Applied pressure 8" (20.3cm) H 2 0 c Applied pressure 12" (30.5 cm) H 2 0 EXAMPLE 16 This example illustrates the preparation of linear alkyl benzene from paraffin dehydrogenate usmg a hydrogen fluonde-treated mordenite catalyst. In the example, benzene was alkylated with a sample of C, 0 -C, 4 paraffin dehydrogenate containmg about 8.5% C| 0 -C. 4 olefins. Alkylation was conducted a process umt as 5 shown in FIG. 1. Alkylation was conducted by first charging 500 ml of a benzene/paraffin dehydrogenate mix (5:1 molar ratio, benzene/C< 0 -C, 4 olefin) to die reboiler and 500 cc of a HF-treated mordemte to die 1.1" (2.8 cm) l.d. reaction zone. The mordemte was held m place usmg Goodloe packmg. The reboiler liquid was dien heated to reflux and a benzene plus C. 0 -C. 4 paraffin dehydrogenate mix (5.1 molar ratio, benzene/C. 0 -C 1 olefin) l o contmuously mtroduced mto die umt above the catalyst column at the rate of 100 cc/hr (LHSV=0.2 hr"'). Under steady state, reflux, conditions liquid product was contmuously withdrawn from the reboiler and water contmuously taken off from e water trap. The crude liquid product was peπodically analyzed by gas chromatography. The reboiler temperature was typically in die controlled range of 131-205 * C. The column head temperature vanability was 76-83 * C. A summary of me analytical results may be found in Table 14 Table 14 - Example 16 Results (Benzene/C, 0 -C 14 Olefin Paraffin Feed) " Corrected for benzene in effluent sample b Composite product EXAMPLE 17 This example illustrates die preparation of linear alkyl benzenes from paraffin dehydrogenate usmg a hydrogen fluoride-treated mordenite catalyst. Following me procedures of Example 14, alkylation of benzene wim C, 0 -C 14 paraffin dehydrogenate was conducted usmg die stainless-steel unit of FIG. 2, complete with an extended catalyst column, reboiler, condenser, and controls. About 750 cc of die HF-treated mordenite of Example B was charged to d e column. The liquid feed comprised benzene plus C 10 -C, 4 paraffin dehydrogenate mix in a 10:1 molar ratio of benzene/C, 0 -C, 4 olefin. The LHSV remained at about 0.13 hr 1 . Alkylation was conducted over a range of column and reboiler temperatures and a range of exit pressures. Typical results are summarized in Table 15. Table 15 - Example 17 Results (Benezene/C )0 -C u Olefin/Paraffin Feed) I rυ ID I I O o I " Corrected for C 6 H 6 in Effluent Sample b Composite Product c Total Heavies Concentration (dialkylated aromatics plus tetralins) less than 0.5% EXAMPLES 18-20 These examples illustrate me preparation of linear alkyl benzene usmg hydrogen fluoπde-modified mordemte catalysts with different fluoπde treatment levels. Followmg me procedures of Example 13, die alkylation unit was charged widi benzene (100 ml), a 10 g sample of hydrogen fluonde-modified mordenite prepared by the procedure of Example B, plus a mix of benzene (50 ml) and 1 -decene (10 g). Three HF- treated mordenites were tested, having die composition Catalyst "C", 0.25% HF on mordenite (CBV-20A); Catalyst "D" 0.50% HF on mordenite (CBV-20A); and Catalyst "E" 1.0% HF on mordemte (CBV-20A). In each experiment, samples of the bottoms liquid fraction were wimdrawn at regular peπods and sub j ect to gas chromatography analyses. The results are summanzed in Table 16. Table 16 - Results of Examples 18-20 (Benzene/ 1-Dodecene Batch) EXAMPLE 21 This example illustrates the inactivity of a heavily loaded hydrogen-fluoπde modified mordemte catalyst. Followmg procedures similar to Example 14, d e alkylation unit was charged widi 100 cc of a hydrogen fluonde-treated mordemte (CBV-20A) prepared by die method of Example B but having a much higher loading of HF (fluonde content 4.8%). The acidity of said HF-treated mordenite was 0.15 meq/g. No significant amount of alkylated product was detected by gas chromatography. COMPARATIVE EXAMPLE 2 This example illustrates die poor performance of die second continuous reactive distillation reactor of Fig. 2 when e C< 0 -C, 4 paraffin dehydrogenate feed component is injected mto the catalyst bed, 132, at die midpoint, 133, radier than above die catalyst column at feed mlet point 114. Following procedures similar to Example 17, the alkylation unit was charged widi 750 cc of me hydrogen fluonde-treated mordenite prepared by die mediod of Example B, but die liquid feed components, benzene and C, 0 -C 14 paraffin dehydrogenate mix, were charged separately to the alkylation umt of FIG. 2 Benzene was charged above die catalyst column at feed mlet point 114 at a rate of 28 cc/hr. The C ]0 -C, 4 paraffin dehydrogenate was charged separately at the midpoint, 133, of me catalyst bed at a rate of 72 cc/hr. Under steady state conditions, widi a reboiler temperature of 170° C and a reaction zone temperature range of 100-142 °C, GLC analysis of typical product effluent liquid yielded die following results: ∑ Alkylate Concentration: 4.9% 2 - Phenyl Isomer Selectivity: 72.2% ∑ C 6 H 6 Concentration: 7.5% ∑ Corrected Alkylate Concentration: 5.3% ∑ Heavies Concentration: 4.0%

Claims: WHAT IS CLAIMED IS: 1. A process useful for prepanng alkylated aromatic compounds, compnsmg: (A) introducing an aromatic compound having from about 6 to about 30 carbons and an olefin 5 having from about 8 to about 30 carbons above a catalyst bed containing an alkylation catalyst; (B) contacting die olefin and me aromatic compound in me presence of die alkylation catalyst under conditions such that me olefin and die aromatic compound react to form an alkylated aromatic compound; (C) allowing die alkylated aromatic compound and any unreacted aromatic compound to l o descend mto a reboiler from the catalyst bed; (D) withdrawing me alkylated aromatic compound from die reboiler; and (E) heatmg contents of d e reboiler such diat me aromatic compound refluxes to contact the catalyst bed. 2. The process of claim 1 , wherein me aromatic compound and the olefin are mtroduced as a mixture. 15 3. The process of claim 1, wherein me aromatic compound and me olefin are introduced separately, and further compnsmg mixing die aromatic compound and d e olefin above the catalyst bed. 4. The process of claim 3, wherein die aromatic compound and d e olefin are mixed by passage through packmg above the catalyst bed. 5. The process of claim 2 or 3, wherem the aromatic compound is benzene. 20 6. The process of claim 5, wherein me olefin has from about 10 to about 14 carbons. 7. The process of claim 5 or 6, further compnsmg collecting water overhead to die catalyst bed in a water trap. 8. The process of claim 5, 6 or 7, further compnsmg mamtammg greater than 0.1% benzene m me reboiler. 25 9. The process of claim 5, 6, 7 or 8, wherein the alkylation catalyst is selected from HF-treated montmoπllomte clay, beta zeolite, mordemte, or HF-treated mordemte. 10. The process of claim 5, 6, 7, 8 or 9, wherem d e benzene and olefin or olefin-paraffin mixture are mtroduced in a benzene/olefin ratio of from about 2:1 to about 20:1, wherem the catalyst bed is maintained at a temperature of from about 70 °C to about 200 °C, and wherein the benzene and olefin or olefin-paraffin 30 mixture are introduced at a combmed liquid hourly space velocity of from about 0.05 hr " ' to about 1.0 hr " '. 11. The process of claim 5, 6, 7, 8, 9 or 10, wherem die benzene and olefin or olefin-paraffin mixture are mtroduced in a benzene/olefin ratio of from about 2 1 to about 20:1, wherem me catalyst bed is mamtained at a temperature of from about 70 °C to about 200 °C, and wherein the benzene and olefin or olefin-paraffin mixture are introduced at a combined liquid hourly space velocity of from about 0.05 hr ' to about 10 hr " '. 35 12. A system for manufacturing alkylated aromatic compounds, compnsmg (A) a reactor containmg an alkylation catalyst bed; (B) one or more injectors in die reactor for introducing aromatic compound, olefin or a mixture of aromatic compound and olefin above the catalyst bed; (C) a reboiler for collecting, heating and refluxmg unreacted aromatic compound descendmg from d e reactor, the reboiler positioned below and in communication with die reactor, die reactor and reboiler bemg generally in vertical alignment; and (D) a means for withdrawing alkylated aromatic compound from the reboiler. 13. The system of claim 12, further compnsmg a means for mixing die aromatic compound and the olefin, the mixing means located above me catalyst bed. 14. The system of claim 13, wherein die mixing means is packing. 15 The system of claim 12, 13 or 14, wherein the alkylation catalyst is selected from HF-treated montmorillonite clay, beta zeolite, mordenite or HF-treated mordemte. 16 The system of claim 12, 13, 14, 15 or 16, further compnsmg a condenser for condensing unreacted aromatic compound and water positioned above and in communication with the reactor. 17. The system of claim 16, further compnsmg a means for collecting water positioned below and in communication with die condenser. 18. The system of claim 17, further compnsmg a means for mcreasmg pressure m the system; the pressure means bemg connected to one or more locations selected from die condenser, water collection means, reactor, injector, reboiler or withdrawal means. 19. The system of claim 18, further compnsmg a means for controlling the liquid level in die system; the liquid level control means bemg connected to one or more locations selected from me wimdrawal means, die reboiler, the reactor, me water collection means or the condenser.

Inventors: ANANTANENI PRAKASA RAO, KNIFTON JOHN F, STOCKTON MELVIN E, ANANTANENI, PRAKASA, RAO, KNIFTON, JOHN, F., STOCKTON, MELVIN, E.
Applicants: HUNTSMAN PETROCHIMICAL CORP, HUNTSMAN PETROCHIMICAL CORPORATION
Application year: 1997
Main classification: C07C15
IPC codes: B01D3, B01J19, B01J29, B01J37, C07C2, C07C15