Patent Application: US-86904201-A

Abstract:
the present invention relates to a catalyst comprising at least one metal loaded on a hydrotalcite - based carrier material which has the following formula in its uncalcined form : m 2 + a m 3 + b 2a + 3 b − n * xh 2 o , wherein m 2 + is at least one divalent metal ; and m 3 + is at least one trivalent metal ; a is an n - valent anion , n is 1 or 2 and a and b are positive numbers , a & gt ; b . when said at least one metal is selected from the group viii of the periodical system of the elements a useful hydrogenation catalyst is achieved .

Description:
powder x - ray diffraction measurements were performed using a siemens d - 5000 diffractometer with cu — k α radiation . the specific surface area was measured using nitrogen by the bet method . xrd and bet analysis results are shown in table 1 and in fig1 – 3 . fig1 : x - ray diffractograms of a sample prepared according to example 2 ; a ) after drying , and b ) after calcination . fig2 : x - ray diffractograms of a sample prepared according to example 7 ; a ) after impregnation , and b ) after impregnation and calcination . fig3 : x - ray diffractogram of a sample prepared according to example 11 ; a ) after impregnation , and b ) after impregnation and calcination . calcination was performed under flowing air ( 100 nml / min ). the sample was heated with a heating rate of 3 ° c ./ min to the final calcination temperature . the duration of the calcination ( at the final calcination temperature ) was 15 hours for carrier materials , and 5 hours for catalysts . after completing the calcination , the sample was cooled with a cooling rate of appx . 2 ° c ./ min . before testing , the catalyst powder was pressed to tablets ( 5 tons pressure , tablet diameter 24 mm ), crushed and sieved to a particle diameter of 0 . 7 – 1 . 0 mm . catalytic testing in dehydrogenation reactions was performed in a fixed bed titanium reactor . the inner diameter of the reactor was 9 mm . a titanium tube of outer diameter 3 mm was located in the centre of the reactor . the reactor temperature was controlled by a thermocouple placed in the 3 mm tube inside the reactor . the catalyst pellets ( appx . 3 g ) were placed on a titanium sinter in the reactor . the total pressure in the reactor was 1 . 1 bar . during propane dehydrogenation ( pdh ), the reaction temperature was 600 ° c . the ghsv was 1000 h − 1 based on propane , and the reaction gas contained 4 . 5 % hydrogen , 32 % propane and remainder steam , on a mole basis . the duration of each test cycle was 24 hours , including regeneration . prior to testing , the catalyst was activated in situ through an ror ( reduction - oxidation - reduction ) treatment at 600 ° c . the ror treatment is described in detail in 1 . catalyst regeneration was performed by oxidative treatment using air diluted with nitrogen . the oxygen content was initially 2 %, and was increased in a stepwise manner to a final level of 21 % ( pure air ). after regeneration , the catalyst was reduced in flowing hydrogen . both the regeneration and reduction steps were carried out at 600 ° c . in the catalytic tests , the selectivity towards propene was generally 97 – 98 %, on mole carbon basis . conversion data from the tests are shown in table 2 . dehydrogenation of other feeds were performed according to the procedure described above , but at different temperatures and pressures : ethane dehydrogenation was performed at 600 – 700 ° c . with a feed ratio : ethane : h 2 : h 2 o = 16 . 5 : 4 . 5 : 79 on a mole basis , and ghsv = 500 h − 1 based on ethane . iso - butane dehydrogenation was performed at 570 – 600 ° c . with a feed ratio : isobutane : h 2 : h 2 o = 32 4 . 5 : 63 . 5 on a mole basis , and ghsv = 1000 h − 1 based on isobutane . propene hydrogenation was performed at 550 ° c . and 2 bar pressure , with a feed molar ratio : c 3 h 6 : h 2 : h 2 o = 23 : 27 : 50 . the ghsv was 1000 h − 1 based on propene . a ) nitrate salts of magnesium ( mg ( no 3 ) 2 * 6h 2 o , 116 . 35 g ) and aluminium ( al ( no 3 ) 3 * 9h 2 o , 17 . 01 g ) were dissolved in distilled water ( 500 ml ). a second solution was prepared from ( nh 4 ) 2 co 3 ( 2 . 18 g ) and nh 3 ( 25 %, 21 ml ) in distilled water ( 500 ml ). the two solutions were slowly added ( dropwise addition with 40 minutes duration ) to a common reservoir under continuous stirring . the ph of the solution was kept constant at appx . 8 , and the temperature was appx . 60 ° c . the final adduct was filtered , washed with distilled water to neutrality , and dried overnight ( 100 ° c .). the x - ray diffractogram showed a major hydrotalcite phase . b ) a part of the product was subject to calcination at 700 ° c . the transformation of the hydrotalcite phase into a mg ( al ) o structure was shown by xrd . chemical analysis of the resulting carrier material showed that it had a molar ratio : mg / al = 3 . a ) nitrate salts of magnesium ( mg ( no 3 ) 2 * 6h 2 o , 233 . 24 g ) and aluminium ( al ( no 3 ) 3 * 9h 2 o , 34 . 02 g ) were dissolved in distilled water ( 1000 ml ). a second solution was prepared from na 2 co 3 ( 4 . 80 g ) and naoh ( 45 . 31 g ) in distilled water ( 1000 ml ). the two solutions were slowly added ( dropwise addition with 55 minutes duration ) to a common reservoir under continuous stirring . the ph of the solution was kept constant at appx . 10 , and the temperature was appx . 60 ° c . the final adduct was filtered , washed with distilled water to neutrality , and dried overnight ( 100 ° c .). the x - ray diffractogram showed a major hydrotalcite phase . b ) a part of the product was subject to calcination at 800 ° c . the transformation of the hydrotalcite phase into a mg ( al ) o structure was shown by xrd . chemical analysis of the resulting carrier material obtained during repeated preparations , showed that it had a molar ratio in the range mg / al = 5 . 0 ± 0 . 6 . the carrier material used for metal addition had a mg / al ratio of 4 . 8 . xrd patterns of the dried and calcined materials are shown in fig1 . impregnation of a calcined htc carrier material from an ethanol solution a ) a mg — al — o carrier material ( 61 . 95 g ) prepared according to example 1b was co - impregnated with h 2 ptcl 6 * 6h 2 o ( 0 . 4930 g ) and sncl 2 * 2h 2 o ( 1 . 4133 g ) in ethanol solution ( 500 ml ). the solution was stirred with the carrier material for 2 hours , and the solvent evaporated under reduced pressure . the solid material was then dried ( 100 ° c .). part of the material was calcined at 560 ° c . and tested under pdh conditions . b ) a mg — al — o carrier material ( 51 . 86 g ) prepared according to example 2b was co - impregnated with h 2 ptcl 6 * 6h 2 o ( 0 . 3889 g ) and sncl 2 * 2h 2 o ( 1 . 1828 g ) in ethanol solution ( 400 ml ). the solution was stirred with the carrier material for 2 hours , and the solvent evaporated under reduced pressure . the solid material was then dried ( 100 ° c .). part of the material was calcined at 560 ° c . and tested under pdh conditions . impregnation of a calcined htc carrier material from an aqueous solution acidified by hcl , without washing tin chloride ( sncl 2 * 2h 2 o , 0 . 3181 g ) was dissolved in hcl ( 2m , 51 ml ). hexachloroplatinum ( h 2 ptcl 6 * 6h 2 o , 0 . 1045 g ) was dissolved in distilled water ( 91 ml ). the two solution were mixed . a mg — al — o carrier material ( 13 . 9 g ) prepared according to example 1b was stirred with the salt solution for 30 minutes . the solution was then filtered , and the solid material dried ( 100 ° c .). the material was calcined at 560 ° c . and tested under pdh conditions . impregnation of a calcined htc carrier material from an aqueous solution acidified by hcl tin chloride ( sncl 2 * 2h 2 o , 0 . 3398 g ) was dissolved in hcl ( 1m , 109 ml ). hexachloroplatinum ( h 2 ptcl 6 * 6h 2 o , 0 . 1116 g ) was dissolved in distilled water ( 40 ml ). the two solutions were mixed . a mg — al — o carrier material ( 14 . 88 g ) prepared according to example 1b was stirred with the salt solution for 30 minutes . the solution was then filtered , and washed 3 times with water ( appx . 750 ml ). the solid material was dried ( 100 ° c .). part of the material was calcined ( 560 ° c .) and tested under pdh conditions . impregnation of a calcined htc carrier material from an aqueous solution acidified by hcl tin chloride ( sncl 2 * 2h 2 o , 0 . 2429 g ) was dissolved in hcl ( 37 %, 6 . 5 ml ). hexachloroplatinum ( h 2 ptcl 6 * 6h 2 o , 0 . 0793 g ) was dissolved in distilled water . the two solutions were mixed and distilled water added to a total volume of 100 ml . the solution was mixed with a calcined mg ( al ) o material , prepared according to example 2b ( 10 . 6 g ). the suspension was stirred for 1 hour , filtered , washed and dried overnight ( 100 ° c .). the product was then calcined ( 560 ° c .) and tested under pdh conditions . impregnation of a calcined htc carrier material in suspension , from an aqueous solution acidified by hcl ( rapid addition ) tin chloride ( sncl 2 * 2h 2 o , 0 . 2482 g ) was dissolved in hcl ( 2m , 32 ml ). hexachloroplatinum ( h 2 ptcl 6 * 6h 2 o , 0 . 082 g ) was dissolved in distilled water ( 5 ml ). the two solutions were mixed . mg ( al ) o ( 10 . 9 g ), prepared according to example 2b , was slurried in distilled water ( 60 ml ). the suspension was stirred for some minutes , before the salt solution was rapidly added . the final suspension was stirred for 1 hour , filtered , washed and dried overnight ( 100 ° c .). the product was then calcined ( 560 ° c .) and tested under pdh conditions . xrd patterns of the dried and calcined materials are shown in fig2 . impregnation of a calcined htc carrier material in suspension , from an aqueous solution acidified by hcl ( dropwise addition ) tin chloride ( sncl 2 * 2h 2 o , 0 . 2094 g ) was dissolved in hcl ( 37 %, 5 . 6 ml ). hexachloroplatinum ( h 2 ptcl 6 * 6h 2 o , 0 . 0691 g ) was dissolved in distilled water ( 10 ml ). the two solution were mixed , and distilled water added to a total volume of 35 ml . mg ( al ) o ( 9 . 18 g ), prepared according to example 2b , was added to distilled water ( 85 ml ). the suspension was stirred for some minutes , before the salt solution was added in a dropwise manner ( 10 min ). the final suspension was stirred for 1 hour , filtered , washed and dried ( 100 ° c .). the product was then calcined ( 560 ° c .) and tested under pdh conditions . in the main test ( ex . 8a ), the ordinary pretreatment procedure was used , while in a second test ( ex . 8b ), a slightly modified pretreatment procedure was used . impregnation of a calcined htc carrier material in suspension , from an aqueous solution acidified by hcl , with prolonged contact time tin chloride ( sncl 2 * 2h 2 o , 0 . 2349 g ) was dissolved in hcl ( 37 %, 6 ml ). hexachloroplatinum ( h 2 ptcl 6 * 6h 2 o , 0 . 0774 g ) was dissolved in distilled water ( 5 ml ). the two solution were mixed , and distilled water added to a total volume of 45 ml . mg ( al ) o ( 10 . 3 g ), prepared according to example 2b , was added to distilled water ( 55 ml ). the suspension was stirred for some minutes , before the salt solution was added in a dropwise manner ( 4 - 5 min ). the final suspension was stirred for 3 hours , filtered , washed and dried overnight ( 100 ° c .). the product was then calcined ( 560 ° c .) and tested under pdh conditions . impregnation of a calcined htc carrier material in suspension , from an aqueous solution acidified by hcl , without washing tin chloride ( sncl 2 * 2h 2 o , 0 . 2015 g ) was dissolved in hcl ( 37 %, 5 . 5 ml ). hexachloroplatinum ( h 2 ptcl 6 * 6h 2 o , 0 . 0670 g ) was dissolved in distilled water ( 10 ml ). the two solution were mixed , and distilled water added to a total volume of 40 ml . mg ( al ) o ( 8 . 83 g ), prepared according to example 2b , was added to distilled water ( 45 ml ). the suspension was stirred for some minutes , before the salt solution was added in a dropwise manner ( 10 min ). the final suspension was stirred for 1 hour , filtered and dried overnight ( 100 ° c .). the product was then calcined ( 560 ° c .) and tested under pdh conditions . impregnation of a calcined htc carrier material in suspension , from an aqueous solution acidified by acetic acid tin chloride ( sncl 2 * 2h 2 o , 0 . 2355 g ) and hexachloroplatinum ( h 2 ptcl 6 * 6h 2 o , 0 . 076 g ) were dissolved in acetic acid ( 10 ml ). distilled water was added to a total volume of 50 ml . mg ( al ) o ( 10 . 2 g ), prepared according to example 2b , was added to distilled water ( 60 ml ). the suspension was stirred for some minutes , before the salt solution was added in a dropwise manner ( 4 – 5 min ). the final suspension was stirred for 0 . 5 hours , filtered and dried overnight ( 100 ° c .). xrd of the dried product showed the appearance of a poorly crystalline hydrotalcite . the d ( 001 ) value had been shifted to 10 . 82 , indicating that the anion interlayer contains acetate anions , ( fig3 a ). the product was then calcined at 560 ° c . yielding the mgo phase ( fig3 b ). impregnation of an uncalcined htc carrier material in suspension , from an aqueous solution acidified by hcl a ) tin chloride ( sncl 2 * 2h 2 o , 0 . 2046 g ) was dissolved in hcl ( 37 %, 6 . 0 ml ). hexachloroplatinum ( h 2 ptcl 6 * 6h 2 o , 0 . 0677 g ) was dissolved in distilled water ( 10 ml ). the two solution were mixed , and distilled water added to a total volume of 40 ml . mg — al htc ( 14 . 7 g ), prepared according to example 2a , was added to distilled water ( 50 ml ). the suspension was stirred for some minutes , before the salt solution was added in a dropwise manner ( 10 min ). the final suspension was stirred for 1 hour , filtered , washed and dried overnight ( 100 ° c .). part of the product was then calcined ( 560 ° c .) and tested under pdh conditions . b ) part of the dried product was calcined at 800 ° c . and tested under pdh conditions . tin chloride ( snc 2 * 2h 2 o , 0 . 1779 g ) and hexachloroplatinum ( h 2 ptcl 6 * 6h 2 o , 0 . 0586 g ) were dissolved in ethanol ( 75 ml ). the solution were added to a mg — al htc ( 12 . 78 g ) carrier , prepared according to example 2a . the suspension was stirred for 2 hours , and the solvent evaporated under reduced pressure . the solid material was dried ( 100 ° c . ), calcined ( 560 ° c .) and tested under pdh conditions . preparation of hydrotalcite material containing mg and ga , with subsequent impregnation nitrate salts of magnesium ( mg ( no 3 ) 2 * 6h 2 o , 73 . 80 g ) and gallium ( ga ( no 3 ) 3 * 9h 2 o , 13 . 411 g ) were dissolved in distilled water ( 750 ml ). a second solution was prepared from k 2 co 3 ( 3 . 355 g ) and koh ( 22 . 57 g ) in distilled water ( 750 ml ). distilled water ( 300 ml ) was added to a reservoir and heated to 50 ° c . the two solutions were added to this reservoir in a dropwise manner ( total duration 40 minutes ) under continuous stirring . the ph of the solution was kept constant at appx . 10 , and the temperature was appx . 45 ° c . the final adduct was filtered , washed with distilled water and dried overnight ( 100 ° c .). the x - ray diffractogram showed a hydrotalcite phase . part of the material was calcined ( 800 ° c .) and impregnated with pt and sn according to example 8 . impregnation of a wet , uncalcined htc carrier material in suspension , from an aqueous solution acidified by hcl a ) tin chloride ( sncl 2 * 2h 2 o , 0 . 2046 g ) was dissolved in hcl ( 37 %, 6 . 0 ml ). hexachloroplatinum ( h 2 ptcl 6 * 6h 2 o , 0 . 0677 g ) was dissolved in distilled water ( 10 ml ). the two solution were mixed , and distilled water added to a total volume of 40 ml . mg — al htc ( 14 . 7 g ) was prepared according to example 2a , but without drying . the salt solution was added to the wet carrier material in a dropwise manner ( 10 min ). the final suspension was stirred for 1 hour , filtered , washed and dried overnight ( 100 ° c .). part of the product was then calcined ( 560 ° c .) and tested under pdh conditions . b ) part of the dried product was calcined at 800 ° c . and tested under pdh conditions . a carrier material prepared according to example 1b was subject to a catalytic test under pdh conditions . gc analysis of the effluent gas showed negligible propane conversion (& lt ; 1 %) under the test conditions described above (& gt ;& gt ; general & gt ;& gt ;), but with shorter residence time ( ghsv = 2400 h − 1 ). the catalysts prepared according to examples 3 – 15 and 20 were subject to catalytic testing under pdh conditions . test results obtained during the first 10 test cycles are shown in table 2 . a ) ethane dehydrogenation . a catalyst prepared according to example 8 was used as an ethane dehydrogenation catalyst ( see & lt ;& lt ; general & gt ;& gt ; for test conditions ). the results obtained during six subsequent test cycles at 650 ° c . showed a stable activity from cycle to cycle , with an initial conversion of 40 %, decreasing to 30 % at the end of each test cycle . the selectivity towards ethene was 80 – 85 %, on mole carbon basis . before testing as an ethane dehydrogenation catalyst , the catalyst had been subject to pdh testing at 600 ° c . b ) isobutane dehydrogenation . a catalyst prepared according to example 8 was used as an isobutane dehydrogenation catalyst ( see & lt ;& lt ; general & gt ;& gt ; for test conditions ). the results obtained during three subsequent test cycles at 590 ° c . showed a rather stable activity from cycle to cycle , with an initial conversion of 58 % ( cycle 1 ), 57 % ( cycle 2 ) and 56 % ( cycle 3 ), decreasing to 44 % at the end of each test cycle . the selectivity towards butenes was 96 %, on mole carbon basis . before testing as an isobutane dehydrogenation catalyst , the catalyst had been subject to pdh testing at 600 ° c . c ) propene hydrogenation . a catalyst prepared according to example 12 was used as a propene hydrogenation catalyst ( see “ general ” for test conditions ). the catalyst had a high initial activity ( 74 % conversion ), decreasing to 32 % during the first test cycle . the propane selectivity was 98 – 99 % throughout the test . a catalyst prepared according to example 8 was subject to calcination at various temperatures ( 560 – 800 ° c .). relative pt dispersion values of the calcined samples were determined by co pulse chemisorption experiments using an alta - mira apparatus ( ami - 1 ) and the ror pretreatment procedure . the results of the co pulse chemisorption experiments are shown in table 3 . xrd showed a major mgo phase for all samples , and the bet area was in the range 150 – 200 m 2 / g for all samples ( table 1 ). pdh testing gave very similar results for the samples calcined at 560 , 700 and 800 ° c . ( table 2 ). it should be noted that these results are not directly comparable with the other results in table 2 , due to a slightly modified pretreatment procedure . a catalyst was prepared according to example 8 , and subsequently mixed with a lumina , before pressing , crushing , sieving and testing as a pdh catalyst . the results shown in table 2 correspond to an alumina content of appx . 20 wt %. similar test results were obtained with other alumina contents . the characterisation results shown in fig1 – 3 and in table 1 illustrate that when contacting a calcined hydrotalcite - based material with an aqueous solution , the hydrotalcite phase is regained . after subsequent calcination , the hydrotalcite phase transforms to the oxide phase . however , when contacting a calcined hydrotalcite - based material with an ethanol solution , the oxide structure is maintained . it has previously ( see : & lt ;& lt ; general & gt ;& gt ;) been stated that the selectivity of the catalysts prepared according to the present invention , is very high . the major focus of this discussion is therefore on the activity and stability of dehydrogenation catalysts prepared according to the present invention . from the results in table 2 , it is observed that the initial conversion level of the catalysts is generally high during propane dehydrogenation ( appx . 60 %), and very close to the thermodynamic equilibrium conversion under these conditions . when discussing the catalyst stability , focus is therefore put on the activity at the end of each test cycle , denoted & lt ;& lt ; final conversion & gt ;& gt ; in table 2 . when reporting that the catalyst reaches a stable performance level , this means that it &# 39 ; s final conversion is similar for several consecutive test cycles . in general , the test results ( table 2 ) illustrate that the catalysts prepared according to the present invention ( i . e . ; metal addition , washing and calcination ) reach a stable performance level between the 5 th and 10 th test cycle . the test results shown in table 2 further illustrate that catalysts prepared according to our previous invention 1 ( i . e . ; oxide phase of carrier material during metal addition , example 3 ), have a life time stability and / or a stable performance level which is clearly inferior to that obtained for samples prepared according to the present invention ( i . e . ; hydrotalcite phase during metal addition , preferably followed by washing , e . g . examples 5 – 9 ). this means that it is important to add the metal ( s ) to the hydrotalcite phase , and then calcine it at the desired temperature . table 2 further illustrates the strong influence of the washing step on the stable performance level of each catalyst ( example 4 vs . example 5 ; and example 8 vs . example 10 ). the same trends are observed regardless of the mg / al ratio of the hydrotalcite - based carrier material . the metal addition procedure ( dry or wet carrier , dropwise or & gt ;& gt ; one go & gt ;& gt ; metal addition , carrier metal solution contact time ) has only a minor influence on the catalyst &# 39 ; s initial activity and life time stability . the characterisation results shown in table 1 and 3 illustrate that the final calcination temperature may be varied compared to the standard calcination temperature ( 560 ° c . ), while maintaining a high metal dispersion and high specific surface area . the corresponding test results ( table 2 ) illustrate that the calcination of the final catalysts at temperatures above 560 ° c . leads to catalysts with maintained or improved long - term stability . the results in table 2 further indicate that the impregnation of an uncalcined hydrotalcite , which is subsequently calcined at 560 ° c ., gives a catalyst with a lower deactivation rate within each test cycle , but with a lesser long - term stability compared to catalysts based on pre - calcined carrier materials . replacing al in the hydrotalcite phase with ga does not lead to an improved catalyst compared to carrier materials containing only mg and al . addition of an alumina binder leads to a more rapid deactivation during each test cycle , but does not alter the long - time stability of the catalyst . the use of a modified pretreatment procedure ( ex . 8b ( and ex . 19 ) compared to ex . 8a ) gave a higher conversion in the first test cycle , but did not alter the long - term stability of the catalyst . the dehydrogenation tests using other feedstocks than propane ( example 18 ) illustrate that the excellent activity and stability properties observed for the catalysts of the present invention , are properties which are of general validity to all types of hydrocarbon dehydrogenation reactions . it is further observed that the catalysts of the present invention are also excellent catalysts for the hydrogenation of unsaturated compounds ( example 18 ). the particular benefits thus obtained by using the catalysts of the present invention were not to be expected in view of the prior art comprising the references as listed below . 1 . akporiaye , d . ; 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