Abstract:
A method for producing a linear paraffin includes providing a natural oil in a feed stream, deoxygenating the natural oil to form a stream comprising paraffins, purifying the stream comprising paraffins to form a purified stream comprising paraffins, and separating a first fraction of paraffin product from the purified stream comprising paraffins. A method for producing a linear olefin includes providing a natural oil in a feed stream, deoxygenating the natural oil to form a stream comprising paraffins, dehydrogenating the stream comprising paraffins to form a stream comprising olefins, purifying the stream comprising olefins to form a purified stream comprising olefins, and separating a first fraction of olefin product from the purified stream comprising olefins.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a Division of copending application Ser. No. 13/427,706 filed Mar. 22, 2012, the contents of which are hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to methods for producing renewable detergent compounds, and more particularly relates to methods for producing linear paraffins and olefins from natural oils. 
       BACKGROUND OF THE INVENTION 
       [0003]    While detergents made utilizing linear paraffin- and olefin-based surfactants are biodegradable, processes for creating linear paraffins and olefins are not based on renewable sources. Specifically, linear paraffins and olefins are currently produced from kerosene extracted from the earth. Due to the growing environmental concerns over fossil fuel extraction and economic concerns over exhausting fossil fuel deposits, there is a demand for using an alternate feed source for producing biodegradable surfactants for use in detergents and in other industries. 
         [0004]    Accordingly, it is desirable to provide methods for producing linear paraffins and olefins from natural oils, i.e., oils that are not extracted from the earth. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, when taken in conjunction with the accompanying drawing and this background of the invention. 
       SUMMARY OF THE INVENTION 
       [0005]    Methods for producing a linear paraffin or olefin product from a natural oil are provided herein. In accordance with an exemplary embodiment, a method for producing a linear paraffin includes providing a natural oil in a feed stream, deoxygenating the natural oil to form a stream comprising paraffins, purifying the stream comprising paraffins to form a purified stream comprising paraffins, and separating a first fraction of paraffin product from the purified stream comprising paraffins. 
         [0006]    In another exemplary embodiment, a method for producing a linear olefin includes providing a natural oil in a feed stream, deoxygenating the natural oil to form a stream comprising paraffins, dehydrogenating the stream comprising paraffins to form a stream comprising olefins, purifying the stream comprising olefins to form a purified stream comprising olefins, and separating a first fraction of olefin product from the purified stream comprising olefins. 
         [0007]    In accordance with yet another exemplary embodiment, a method for producing a linear paraffin and a linear olefin includes providing a natural oil in a feed stream, deoxygenating the natural oil to form a stream comprising paraffins, separating the stream comprising paraffins into a first portion comprising paraffins and a second portion comprising paraffins, purifying the first portion comprising paraffins to form a purified stream comprising paraffins, and separating a first fraction of paraffin product from the purified stream comprising paraffins. The method further includes dehydrogenating the second portion comprising paraffins to form a stream comprising olefins, purifying the stream comprising olefins to form a purified stream comprising olefins, and separating a first fraction of olefin product from the purified stream comprising olefins. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0008]    Embodiments of the present invention will hereinafter be described in conjunction with the following drawing figure, wherein: 
           [0009]      FIG. 1  schematically illustrates a system utilizing a process for producing linear paraffins and/or olefins from natural oils in accordance with an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    The following Detailed Description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding Background or the following Detailed Description. 
         [0011]    Various embodiments contemplated herein relate to methods and systems for producing a linear paraffin or olefin product from natural oils. In  FIG. 1 , an exemplary system  10  utilizing an exemplary process for producing a linear paraffin and/or olefin product from a natural oil feed  14 . As used herein, natural oils are those derived from plant or algae matter, and are often referred to as renewable oils. Natural oils are not based on kerosene or other fossil fuels. In certain embodiments, the natural oils include, but are not limited to, one or more of coconut oil, babassu oil, castor oil, algae 1 byproduct, beef tallow oil, borage oil, camelina oil, Canola® oil, choice white grease, coffee oil, corn oil,  Cuphea Viscosissima  oil, evening primrose oil, fish oil, hemp oil, hepar oil, jatropha oil,  Lesquerella Fendleri  oil, linseed oil,  Moringa Oleifera  oil, mustard oil, neem oil, palm oil,  perilla  seed oil, poultry fat, rice bran oil, soybean oil, stillingia oil, sunflower oil, tung oil, yellow grease, cooking oil, and other vegetable, nut, or seed oils. Other natural oils will be known to those having ordinary skill in the art. The natural oils typically include triglycerides, free fatty acids, or a combination of triglycerides and free fatty acids, and other trace compounds. 
         [0012]    In the illustrated embodiment, the natural oil feed  14  is delivered to a deoxygenation unit  16 , which also receives a hydrogen feed  18 . In the deoxygenation unit  16 , the triglycerides and fatty acids in the feed  14  are deoxygenated and converted into linear paraffins. The deoxygenation unit  16  can be configured to catalytically deoxygenate the natural oils. Structurally, triglycerides are formed by three, typically different, fatty acid molecules that are bonded together with a glycerol bridge. The glycerol molecule includes three hydroxyl groups (HO—), and each fatty acid molecule has a carboxyl group (COOH). In triglycerides, the hydroxyl groups of the glycerol join the carboxyl groups of the fatty acids to form ester bonds. Therefore, during deoxygenation, the fatty acids are freed from the triglyceride structure and are converted into linear paraffins. The glycerol is converted into propane, and the oxygen in the hydroxyl and carboxyl groups is converted into either water or carbon dioxide. The deoxygenation reaction for fatty acids and triglycerides are illustrated, respectively, as: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    During the deoxygenation reaction, the length of a product paraffin chain R n  will vary by a value of one depending on the exact reaction pathway. For example, if carbon dioxide is formed, then the chain will have one fewer carbon than the fatty acid source (R″). If water is formed, then the chain will match the length of the R″ chain in the fatty acid source. Typically, due to the reaction kinetics, water and carbon dioxide are formed in roughly equal amounts, such that equal amounts of C X  paraffins and C X-1  paraffins are formed. 
         [0013]    In  FIG. 1 , a deoxygenated stream  20  containing linear paraffins, water, carbon dioxide and propane exits the deoxygenation unit  16  and is fed to a separator  22 . The separator  22  may be a multi-stage fractionation unit, distillation system, or similar known apparatus. In any event, the separator  22  removes the water, carbon dioxide, and propane from the deoxygenated stream  20 . Further, the separator  22 , or optionally another separator, may provide a means to separate the paraffins into various desirable fractions. For example, as shown in  FIG. 1 , a first portion of paraffins  24  and a second portion of paraffins  26  are illustrated, although any number of paraffin portions may be provided, depending on how many paraffin fractions are desired. In certain embodiments, the first portion of paraffins  24  has carbon chain lengths of C 10  to C 14 . In other embodiments, the first portion of paraffins  24  has carbon chain lengths having a lower limit of C L , where L is an integer from four (4) to thirty-one (31), and an upper limit of C U , where U is an integer from five (5) to thirty-two (32). The second portion of paraffins  26  may have carbon chains shorter than, longer than, or a combination of shorter and longer than, the chains of the first portion of paraffins  24 . In one particular embodiment, the first portion of paraffins  24  includes paraffins with C 10  to C 14  chains and the second portion of paraffins  26  includes paraffins with C 18  to C 20  chains. 
         [0014]    Either or both paraffin portions  24  or  26  (or other portions if more are present) may thereafter be purified to remove trace contaminants, resulting in a purified paraffin product. In some embodiments, wherein only paraffin production is desired, the entire paraffin product (i.e., all of the one or more portions) may be purified at this stage. In other embodiments, some of the paraffin product is directed to further processing stages for the production of olefins. In still other embodiments, wherein only olefin production is desired, the entire paraffin product (i.e., all of the one or more portions) may be directed to further processing stages. As shown in the example embodiment illustrated in  FIG. 1 , the second paraffin portion  26  is directed to a purification system  80  to remove trace contaminants, such as oxygenates, nitrogen compounds, and sulfur compounds, among others. In one example, purification system  80  is an adsorption system. Alternatively or additionally, a PEP unit  82 , available from UOP LLC, may be employed as part of purification system  80 . Subsequent to purification, a purified paraffins stream  13  is removed from the system  10  as the paraffin product. 
         [0015]    As further shown in  FIG. 1 , the first portion of paraffins  24  (i.e., that portion of linear paraffins directed for further processing to linear olefins, where desired) is introduced to a linear olefin production zone  28 . Specifically, the first portion of paraffins  24  is fed into a dehydrogenation unit  30  in the olefin production zone  28 . In the dehydrogenation unit  30 , the first portion of paraffins  24  are dehydrogenated into mono-olefins of the same carbon numbers as the first portion of paraffins  24 . Typically, dehydrogenation occurs through known catalytic processes, such as the commercially popular Pacol process. Conversion is typically less than 90%, leaving greater than 10% paraffins unconverted to olefins. Di-olefins (i.e., dienes) and aromatics are also produced as an undesired result of the dehydrogenation reactions as expressed in the following equations: 
         [0000]      Mono-olefin formation: C X H 2X+2 →C X H 2X +H 2  
 
         [0000]      Di-olefin formation: C x H 2X →C X H 2X−2 +H 2  
 
         [0000]      Aromatic formation: C X H 2X−2 →C X H 2X−6 +2H 2  
 
         [0016]    In  FIG. 1 , a dehydrogenated stream  32  exits the dehydrogenation unit  30  comprising mono-olefins and hydrogen, unconverted paraffins, as well as some byproduct di-olefins and aromatics. The dehydrogenated stream  32  is delivered to a phase separator  34  for removing the hydrogen from the dehydrogenated stream  32 . As shown, the hydrogen exits the phase separator  34  in a recycle stream of hydrogen  36  that can, in some embodiments, be added to the hydrogen feed  18  to support the deoxygenation process upstream. 
         [0017]    At the phase separator  34 , a liquid stream  38  is formed and includes the mono-olefins, the unconverted paraffins, and any di-olefins and aromatics formed during dehydrogenation. The liquid stream  38  exits the phase separator  34  and enters a selective hydrogenation unit  40 . In one exemplary embodiment, the hydrogenation unit  40  is a DeFine® reactor (or a reactor employing a DeFine® process), available from UOP LLC. The hydrogenation unit  40  selectively hydrogenates at least a portion of the di-olefins in the liquid stream  38  to form additional mono-olefins. As a result, an enhanced stream  42  is formed with an increased mono-olefin concentration. 
         [0018]    As shown, the enhanced stream  42  passes from the hydrogenation unit  40  to a lights separator  44 , such as a stripper column, which removes a light end stream  46  containing any light hydrocarbons, such as butane, propane, ethane and methane, that resulted from cracking or other reactions during upstream processing. With the light hydrocarbons  46  removed, stream  48  is formed and may be delivered to an aromatic removal apparatus  50 , such as a PEP unit available from UOP LLC. As indicated by its name, the aromatic removal apparatus  50  removes aromatics from the stream  48  and forms a stream of mono-olefins and unconverted paraffins  52 . 
         [0019]    In a further processing step, the unconverted paraffins are separated from the olefins using a separator  56 . In one particular embodiment, the separator  56  is an Olex® separator, available from UOP LLC. The Olex® process involves the selective adsorption of a desired component (i.e., olefins) from a liquid-phase mixture by continuous contacting with a fixed bed of adsorbent. In another particular embodiment, the separator  56  is a direct sulfonation separator. The separated, unconverted paraffins may optionally be directed back to the second paraffin portion  26  for purification (stream  72 ) and/or back to the first paraffin portion  24  for dehydrogenation for conversion to olefins (stream  70 ). 
         [0020]    In  FIG. 1 , an olefins stream  60  exits the separator  56  and is fed to a separator  62 . The separator  62  may be a multi-stage fractionation unit, distillation system, or similar known apparatus. The separator  62  may provide a means to separate the olefins into various desirable fractions. For example, as shown in  FIG. 1 , a first portion of olefins  64  and a second portion of olefins  66  are illustrated, although any number of olefin portions may be provided, depending on how many olefin fractions are desired. In certain embodiments, the first portion of olefins  64  has carbon chain lengths of C 10  to C 14 . In other embodiments, the first portion of olefins  64  has carbon chain lengths having a lower limit of C L , where L is an integer from four (4) to thirty-one (31), and an upper limit of C U , where U is an integer from five (5) to thirty-two (32). The second portion of olefins  66  may have carbon chains shorter than, longer than, or a combination of shorter and longer than, the chains of the first portion of olefins  64 . In one particular embodiment, the first portion of olefins  64  includes olefins with C 10  to C 14  chains and the second portion of olefins  66  includes olefins with C 18  to C 20  chains. Subsequent to separation, the purified olefins portions  64  and  66  are removed from the system  10  as the olefin product. 
         [0021]    With reference now to exemplary natural oil feeds  14 , in certain embodiments, the feed  14  is substantially homogeneous and includes free fatty acids within a desired range. For instance, the feed may be palm fatty acid distillate (PFAD). Alternatively, the feed  14  may include triglycerides and free fatty acids that all have carbon chain lengths appropriate for a desired alkylbenzene product  12 . 
         [0022]    In certain embodiments, the natural oil source is castor, and the feed  14  includes castor oils. Castor oils consist essentially of C 18  fatty acids with additional, internal hydroxyl groups at the carbon-12 position. For instance, the structure of a castor oil triglyceride is: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    During deoxygenation of a feed  14  comprising castor oil, it has been found that some portion of the carbon chains are cleaved at the carbon-12 position. Thus, deoxygenation creates a group of lighter paraffins having C 10  to C 11  chains resulting from cleavage during deoxygenation, and a group of non-cleaved heavier paraffins having C 17  to C 18  chains. The lighter paraffins may form the first portion of paraffins  24  and the heavier paraffins may form the second portion of paraffins  26 . It should be noted that while castor oil is shown as an example of an oil with an additional internal hydroxyl group, others may exist. Also, it may be desirable to engineer genetically modified organisms to produce such oils by design. As such, any oil with an internal hydroxyl group may be a desirable feed oil. 
         [0023]    While at least one exemplary embodiment has been presented in the foregoing Detailed Description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing Detailed Description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended Claims and their legal equivalents.