WO2013141887A1

WO2013141887A1 - Process and apparatus for the selective dimerization of terpenes and alpha-olefin oligomers with a single-stage reactor and a single-stage fractionation system

Info

Publication number: WO2013141887A1
Application number: PCT/US2012/035146
Authority: WO
Inventors: Michael E. Wright
Original assignee: The Government Of The United States Of America As Represented By The Secretary Of The Navy
Priority date: 2012-03-21
Filing date: 2012-04-26
Publication date: 2013-09-26

Abstract

A process and apparatus for dimerization are disclosed. The process includes introducing at least one feedstock which includes an olefin selected from the group consisting of terpenes, alpha-olefin oligomers (AOO), and related olefins and introducing at least one solid acid catalyst to the feedstock for isomerization. The initial heat of isomerization can be recovered and utilized. A first fractionation is used for evaporation of unreacted feedstock, the first fractionation process reducing a pressure of the unreacted feedstock. The concentration of reacting olefin during the isomerization is adjusted via an active recycle protocol. This process produces dimerized products and suppresses formation of oligomers of the olefin, and also enables utilizing a lowered reaction temperature during the isomerization to extend the lifetime of the catalyst. A dimerized product having less than 5 wt. % total of the oligomers of the olefin combined is produced.

Description

PROCESS AND APPARATUS FOR THE SELECTIVE DIMERIZATION OF TERPENES AND ALPHA-OLEFIN OLIGOMERS WITH A SINGLE-STAGE

REACTOR AND A SINGLE-STAGE FRACTIONATION SYSTEM

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0001] The invention described herein may be manufactured and used by or for the government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

FIELD OF THE INVENTION

[0002] The invention generally relates to improved processes and apparatuses for the selective reaction of terpenes (including mono-, sesqui-, di-terpenes, and others in the terpene family), alpha-olefin oligomers (AOO's), and related mono-unsaturated olefins to their respective dimeric product in high purity using heterogeneous acid catalysis concurrent with full utilization of energy created in the process.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] FIG. 1 is a block diagram of a process for the dimerization of terpenes, alpha-olefin oligomers, or related olefins, according to embodiments of the invention.

[0004] FIG. 2 is a block diagram of a process for the dimerization of terpenes, alpha-olefin oligomers, or related olefins that includes hydrogenation of the dimer product for use in diesel and turbine fuels, according to embodiments of the invention.

[0005] FIG. 3 is a block diagram of a process for the dimerization of terpenes, alpha-olefin oligomers, or related olefins that includes hydrogenation of the dimer product, and then hydrocracking/reforming of the hydrogenated dimer to products useful as gas, diesel and turbine fuels, according to embodiments of the invention.

[0006] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not to be viewed as being restrictive of the invention, as claimed. Further advantages of this invention will be apparent after a review of the following detailed description of the disclosed embodiments, which are illustrated schematically in the accompanying drawings and in the appended claims.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

[0007] Embodiments of the invention generally relate to improved processes and apparatuses for the selective reaction of terpenes (including mono-, sesqui-, di-terpenes, and others in the terpene family), alpha-olefin oligomers (AOO's), and related unsaturated olefins to their respective dimeric product in high purity using heterogeneous acid catalyst concurrent with full utilization of energy created in the process. Embodiments of the invention carry out the efficient dimerization of terpenes, alpha-olefin oligomers (AOO's), and olefins using cost effective catalysts and low cost equipment that are ideally suited for commercialization of jet/turbine and diesel biofuel production processes, enabling producing fuels with high flashpoints and superb cold flow properties.

[0008] An aspect of the invention relates to a dimerization process which includes introducing, e.g., to a first reactor, at least one olefin-based composition (or feedstock) which includes an (unsaturated) olefin. The olefin may be selected from the group consisting of terpene(s), alpha-olefin oligomers) (AOO), and related olefins, such as those which can be isomerized by protonation. The method further includes contacting the feedstock with least one solid acid catalyst to for isomerization. The initial heat of isomerization is recovered and utilized, e.g., in a first fractionation process that mildly reduces pressure of unreacted feedstock from the first reactor for the evaporation of the olefin in the unreacted feedstock which can be returned to the isomerization via an active recycle protocol. This enables adjusting, e.g., maximizing the concentration of reacting olefin during protonation and also allows utilizing a minimum reaction temperature to extend the catalyst lifetime, suppressing trimer and other oligomer formations from the olefin, to produce dimerized products substantially in the absence of oligomers, such trimers, tetramers, and up to octamers, to produce a purer dimerized product having less than 5 wt. % total of the trimers and other oligomers of the olefin combined.

[0009] A dimer of the olefin generally refers to a dimer derived from the unsaturated olefin that includes no more than two units derived from the unsaturated olefin. An oligomer of the olefin generally includes more than two units, such as at least three units derived from the unsaturated olefin. The feedstock can include at least 5 wt. %, or at least 10 wt. %, or at least 20 wt. %, or at least 50 wt. % of the unsaturated olefin. The dimerized product can include less than 5 wt. %, or less than 2 wt. % or less than 1 wt. % total of the trimers and other oligomers of the olefin combined. The dimerized product can include a ratio of the dimers: the oligomers of at least 95:5 or at least 98:2 or at least 99:1.

[0010] Embodiments of the method may further include initially diluting of the feedstock/oligomer. Embodiments of the invention include the at least one terpene being selected from the group consisting of monoterpenes, sesquiterpenes, diterpenes, terpenes being linear or having more than one ring, terpenes having at least one site being unsaturated, terpenes having at least one double bond that can be hydrogenated, and terpenes having from about C₅ to about C₃₀ carbons. Other embodiments include at least one terpene being acyclic (including farnesene) and/or cyclic (including limonene). Embodiments of the invention include the at least one AOO having about C₆ to about C₂₈ carbons. Other embodiments include at the least one AOO including bio-2- ethyl-l-hexene.

[0011] In embodiments of the invention, the active recycle protocol can be performed by diluting the feedstock with the recycled and isomerized olefins. The first fraction process can be performed with at least one evaporator selected from the group consisting of at least one wiped film evaporator, a thin film evaporator, and other flash type distillation operation systems. The first fraction process can be performed with more than one column. Yet other embodiments of the invention include a first fraction process output being recycled into the protonation dimerization process for complete conversion to dimer products. Still yet other embodiments include, prior to the first fractionation process sing a monitoring system to detect for presence of oligomers.

[0012] Embodiments of the invention may include reducing pressure during the first fractionation process to such a level that the boiling temperature of isomerized yet non-dimerized feedstock matches the target temperature of the protonation/dimerization process. Embodiments of the invention further include processing either dimerized product through hydrogenation to produce fully saturated hydrocarbon dimer products that can be directly placed in use as diesel and jet/turbine fuels with a flashpoint greater than 61. Embodiments of the invention include the hydrogenation process being selected from the group consisting of at least one trickle bed reactor and/or fixed volume reaction vessel with mechanical stirring. The method may include introducing at least one hydrogenation catalyst into the hydrogenation process. The at least one catalyst can be a transition metals selected from the group palladium, platinum, nickel, and any combination thereof.

[0013] Embodiments of the invention further include processing fully saturated hydrocarbon dimer products through a hydrocracking reactor process to reduce the molecular weight of the saturated hydrocarbon dimer products and/or to produce a lower boiling fuel product. At least one hydrocracking catalyst may be into the hydrocracking process. The at least one hydrocracking catalyst may be selected from the group consisting of palladium, platinum, and nickel or combination thereof and may be supported on a high surface substrate selected from the group consisting of silicate, aluminate, zeolite, and other mesoporous inorganic supports. The hydrogenation process and/or the hydrocracking process may include introducing at least one reagent. The reagent can include H₂. Embodiments of the invention further including processing the lower boiling fuel product of such a hydrocracking through a second fractionation process to produce a fully saturated hydrocarbon biofuel with sufficient flashpoint and cold flow properties.

[0014] Another aspect of the invention includes a dimerized product derived from an olefin-based composition (or feedstock) which is produced by the exemplary method.

[0015] Another aspect of the invention includes a saturated hydrocarbon biofuel which includes a dimerized product produced by the exemplary method or a derivative thereof.

[0016] Other aspects of the invention include a dimer product having no more than 2 wt. % combined total mass of trimer, tetramer, and oligomers, which is produced by the process, e.g., up to 1 wt. %. Another embodiment of the invention includes a fully saturated hydrocarbon gas, diesel, jet/turbine biofuel produced by the process.

[0017] Another aspect of the invention relates to a dimerization system for converting oligomers into dimer products. The system includes components for performing the exemplary method.

[0018] Another aspect of the invention relates to a dimerization system for converting olefins into dimer products. The system includes a source of at least one feedstock comprising an olefin selected from the group consisting of terpene(s), alpha-olefin oligomers), and related olefins, a first reactor in which at least one solid acid catalyst is contacted with said feedstock for isomerization by protonation, wherein said feedstock and said catalyst are processed, a heat collector for recovering and utilizing the initial heat of said isomerization, e.g., for heating a second reactor. The second reactor is configured for performing a first fractionation process which separates unreacted olefin from a fluid exiting from the first reactor, the second reactor having an outlet for reducing pressure of the fluid. A recycle flow path returns the separated olefin from the second reactor to the first reactor to adjust the concentration of reacting olefin during the protonation, which enables lowering reaction temperature in the first reactor to extend the catalyst lifetime and decreasing oligomer formations. The system is able to produce dimerized products of the olefin with reduced concentrations of oligomers of the olefin.

[0019] The dimerization of simple olefins like isobutylene (2-methylpropene) has played a major role in the production petroleum based fuels. These fuels are often referred to as "polymer gasoline." Methods to both simplify and make the process more efficient have been the topic of many patents over the past three plus decades. Methods are continually sought that provide higher selectivity of the targeted produces) and utilize a minimum of steps and hardware. With the advent and interest in dimerizing larger olefins and bioalkenes, for example terpenes and bio(alpha-olefin oligomers), several new considerations arise.

[0020] Modern oligomerization/dimerization strategies have utilized solid phase catalyst such as Amberlyst-15, solid phosphoric acids, and acid modified clays. U.S. patent 7,803,978 (1984) describes a process using a water soluble oxygenate modifier, such as an alcohol, in conjunction with two oligomerization reactors. This process demonstrates the use of Amberlyst-15 catalysts in the process and is primarily focused on isobutylene chemistries.

[0021] US Patent 5,877,372 (1999) describes the dimerization of isobutylene using Amberlyst-15, tertiary butyl alcohol as an "enhancing modifier," and isooctane as a diluent in the simulated process. This improved process claims a 90% selectivity to dimer for an isobutylene feed.

[0022] A process for dimerizing light olefins is described in US Patent 6,660,898 (2003) where unreacted light olefin is recovered by using a reversible chemical reaction. The premise of the invention is again the use of an alcohol, typically tertiary butyl alcohol, as the "selectivity improving oxygenate." This oxygenate must be related to the light olefin in structure or otherwise a complicated product mixture would result that incorporated the oxygenate' s carbon skeleton.

[0023] A process and apparatus for oligomerization is described in US Patent 7,803,978 (2010) where at least two oligomerization reactors are utilized in the process. The simulated process described in the patent relates to the oligomerization of light olefins to create "gasoline range product" using a series of oligomerization reactors interconnected. This simulated process also utilizes an "oxygenate modifier" in the process to create gasoline like products. Additional work by the UOP group (UOP LLC, Des Plaines, IL (US)) was described in US Patent 8,052,945 (2011) with little change in the process and utilizes an alcohol modifier with simulation of only isobutylene as the light olefin.

[0024] Attempts have been made to dimerize terpenes using a solid acid-catalyst. In one attempt (US Patents 4922047, 5847247, and US Application Ser. No. 12/550973 filed on 8/31/2009) conversion was achieved in the process where the monoterpene β-pinene was reacted. US Patent 4922047 focused on producing mixtures of unreacted terpenes and the dimerized product for use as a solvent. The second patent produced significant trimer product with a specific aim of creating lubricants. Other work in the literature has reported that solid acid catalysts, like Amberlyst- 15 and K-Montmonorillite lead to isomerization with only poor conversion to the dimer product when reacting the 2-ethylhexene (Harvey and Quintanna Energy & Fuels 2010) in the presence of Amberlyst- 15. In order to achieve reasonable conversions, the expensive fluorinated sulfonic acid resin, Nafion, was required.

[0025] What is instantly achieved in this invention is a method for efficiently and selectively dimerizing terpenes, AOO's, and related olefins using common solid acid catalysts and in particular sulfonated-polystyrenes or acid clays. Unlike previous work that has focused on isobutylene or 2- butene, the chemical feeds presented in embodiments of this invention can be large and more complicated chemical structures and in particular, can undergo isomerization reactions, skeletal rearrangements, and/or oligomerization polymerization reactions. The feedstocks discussed in embodiments of this invention may be formed directly or indirectly from a biotic process (e.g. fermentation of biomass). Hence, conversion and chemistry performed on these feedstocks should be vigilant to reduce green house gas (GHG) emissions during dimerization and ultimately in a life cycle analysis of the finished biofuel. The instant result of embodiments of this invention is a process that can dimerize a wide array of terpenes, AOO's, and related olefins to diesel and turbine fuels with flashpoints over 61 deg C using an energy and chemically efficient process and apparatus.

[0026] Previously, only rather expensive solid supported acid catalysts were thought to be able to dimerize AOO's effectively. Embodiments of the invention provide a unique method for carrying out dimerization of AOO's and other terpenes that pose difficulty in dimerization. Currently there is no process or apparatus that takes AOO's and converts them to dimeric products using cost- effective reagents. Embodiments of the invention solve an important limitation to current technology in the area and are critical to the success of jet and diesel biofuel production, in particular, where high (61 °C or greater) flashpoints are desired. It also is advantageous for advancement of using terpene and related biofeedstocks.

[0027] A dimerization process and apparatus is described where a single catalyst column feeds a single and simple fractionation. The feed of new terpene or AOO is blended with recycle from the single-fraction column at such a rate and ratio that a preselected reaction temperature can be maintained while the heat of isomerization (i.e. excess heat generated), is captured and utilized in the fractionation column. Embodiments of the invention create dimerized products in the absence of trimeric and other by-products, significantly maximize production rates of the desired dimers, harness/capture all energy in the process, and enables longer catalyst lifetime due to reduced reaction temperatures. The products from this process are useful as fuels and/or precursors diesel and turbine/jet fuels.

[0028] Embodiments of the invention are based upon the concepts of recovering and utilizing the initial heat of isomerization, maximizing the concentration of reacting olefin during protonation/dimerization, utilizing a minimum temperature in the reaction zone to extend catalyst lifetime, and decreasing or eliminating trimer and oligomer formation via an active recycle protocol. By combining these chemical and engineering factors embodiments of this invention bring to light considerable advantage in the art of preparing dimeric chemicals from a feed of terpenes, alpha- olefin oligomers, and related monounsaturated olefins. Prophetic Examples

[0029] The following prophetic examples are for illustration purposes only and not to be used to limit any of the embodiments.

[0030] The "isomerization/dimerization zone" includes solid acid catalysts such as Amberlyst-15 or Amberlyst-36. The initial start up of the feed can be diluted with finished dimer product (hydrogenated ideally) or previously isomerized feed to adequately control the heat output. The initial heat of isomerization can be significant for certain feeds and not for others. Once isomerized through protonation, the dimenzation is a much less exothermic reaction or possibly endothermic in some cases used in embodiments of the invention.

[0031] For the purposes of embodiments of the invention, the "fractionation zone" typically designates a flash type distillation operation under mildly reduced pressure to reduce the pressure of the incoming feed. Multiple columns may be used but a single column is used in this example and one of significant surface area to provide an energy efficient evaporation of the unreacted feed olefin. For example, this can be a thin film evaporator or wiped film evaporator with the bottoms feed directly to a storage tank or directly to the next unit (i.e. hydrogenation process). Embodiments of the invention work when dimerizing feedstocks of 6 to 20 carbons and is particularly useful for molecules having 8 to 15 carbons. This group is represented by monoterpenes, sesquiterpenes, and AOO's where very large distillation differences exist between the feed and dimerized product. Furthermore, this process is of particular value where consideration of thermal stability for the feed and/or dimer product is considered as often the case for certain biomaterials.

[0032] The "hydrogenation zone" is typically operated as a trickle-bed type of reactor at pressures ranging from 50 to 2000 psig and temperature ranging, but not limited from, about 50 to about 150 °C. Other ranges of pressure and temperature can be useful in embodiments of the invention when faster processing is required or the feedstock has limited temperature stability. Alternatively, a continuous batch-process can be employed using a fixed volume reactor vessel with mechanical stirring. For each new feed and dimer product the process is optimized to minimize heating and balance heating requirements with the heat output of isomerization and dimerization. This batch- process does expose the dimer to longer heating times although in the absence of acid catalyst; hence, trimer formation is still eliminated in this improved process. [0033] A "hydrocracking zone" can be added to the process to further tailor the process and apparatus to produce a lower boiling fuel product yet retain a high flashpoint and utilize at least 80% of the original carbon. In some cases this is not necessary and in others a minimum of hydrocracking may be necessary to adjust viscosity, flashpoint, and/or cold flow properties in a way common to those experienced in the art of fuel reformation. Common catalysts for this hydrocracking of the dimers would be metal oxides and typical hydrogen pressures would be 100- 2000 psig. Heating would vary depending on the degree of cracking required by substrate and target product.

[0034] The hydrocarbon feed used in embodiments of the invention can be neat olefin and it is stressed does not include an oxygenate species. In some cases it may be best to initially dilute the feed with previously isomerized hydrocarbon olefin (also can be hydrogenated) or the product of dimerization is suitable. Once in steady state operation, the recycled and isomerized olefin serves to dilute the feed olefin, thus controlling heat out in the isomerization/dimerization zone. The extent of isomerization should be nearly 100% complete in the isomerization dimerization zone and dimer formation should be about 5% to about 80% and can be controlled by choice of catalyst, time exposed to the catalyst, and temperature maintained for the isomerization/dimerization zone. Conditions and time in contact with the catalyst should be mild and short enough, respectively, as to avoid formation of trimer, tetramer, and oligomeric product. Suitable feeds for this invention include terpenes of about 5 to about 30 carbons, AOO's of about 6 to about 28 carbons, other mono- and di- olefins of about 5 to about 30 carbons.

[0035] In some embodiments of this invention in which a C₈-hydrocarbon AOO is dimerized, the initial feed may include about 50% of the finished (i.e., hydrogenated) Ci₆-dimer product. The feed can consist of an AOO obtained from biomass through a dehydration/oligomerization process starting with bioalcohols, or be obtained directly from a biological process, or from a petroleum feed involving olefin processing. The C₈-AOO obtained from biobutanol is one such feedstock, namely bio-2-ethyl-l-hexene. When obtained using a Ziegler-Natta process from bio-l-butene, the AOO produced (2-ethyl-l-hexene) is a single regio-isomer as shown:

2-ethyl-1-hexene

[0036] The 2-ethyl-l-hexene undergoes a rapid acid-catalyzed isomerization reaction that is highly exothermic. Although concurrent dimerization can and will occur to some extent, it is relatively slow compared to isomerization of the AOO that is driven by formation of the more thermodynamically stable internal olefin mixture, which yield C₁ dimer products on further reaction:

2-ethyl-1-hexene

C₁₆-dimer products

[0037] In other embodiments of the invention in which terpene feedstocks are dimerized, the feedstock compound can be selected from a group of monoterpenes (Cio), sesquiterpene (C15), diterpene (C20), and/or larger hydrocarbon terpenes. The terpene may be linear or include one or more rings in the chemical structure. In embodiments where the terpene has more than one site of unsaturation, one or more of the double bonds can be hydrogenated prior to dimerization to produce higher selectivity in the dimerization reaction [Driessen-Holscher in Adv. Catalysis, 42, pp 473-505 (1998)]. There are several catalytic systems available for the selective hydrogenation of terpenes including two or more sites of unsaturation. These latter catalysts are effective for both acyclic terpenes including farnesene and cyclic-terpenes such limonene:

[0038] Yet in other embodiments of the invention, a terpene alcohol is hydrogenated, then dehydrated, and this mono-unsaturated terpene is used as the olefin feed. Since the terpene is fully isomerized to a thermodynamic mixture of internal olefins, no significant exothermic event will occur upon contact with the acid catalyst and thus no initial dilution of the olefin feed is required in some embodiments:

Linalool

monoterpene alcohol

C₂o-dimers

[0039] Embodiments of the invention specifically aim to provide a continuous flow system capable of dimerizing terpenes, AOO's, and other olefins to their respective dimers in 100% conversion with better than 98% selectivity for the dimer product. Furthermore, embodiments teach how to utilize inexpensive solid acid-catalysts systems and a means to provide exceptional long catalyst life by optimizing reaction conditions. The dimer products created in embodiments of the invention can be further processed to afford diesel and/or turbine/jet petro- and bio-fuels with flashpoints greater than 61 °C, such as at least 62 °C or at least 65 °C.

[0040] FIG. 1 shows, in the form of a block diagram, the process flow scheme for converting terpenes, AOO, or olefins to dimeric products. A feedstock is fed from a source 10 to a reactor Rl. Depending on the feed to the isomerization/dimerization reactor Rl, a valve VI from the diluent source may be used as needed to control the heat generated in the catalyst bed in the reactor Rl. Typically, the catalyst bed will be included in a jacketed tube-reactor Rl. The jacket 20 serves as a heat collector that can pull off the heat and transfer the heat to the fractionator R2 and/or spread the heat uniformly over the entire length of Rl. The liquid exiting Rl is monitored with a monitoring system 24 to detect formation of oligomers (trimer, and above) and look to reaching a maximum conversion to dimer. Monitoring system 24 can be placed in the fluid flow path 18 connecting Rl and R2 or in the reactor Rl itself. When trimer is detected, faster flow rates are applied and/or the temperature is reduced. The process is tuned/optimized for each feed used in the apparatus shown in FIG. 1. Conversion rates to dimer may be between 5 and 80% in a single pass depending on the type of feed and chemical structure. The mixture exiting Rl is all directed to reactor R2 which is a high-surface area fractionation device (e.g. a wiped film evaporator) operating under reduced pressure (as compared with the pressure of incoming received mixture from Rl). For example an outlet 14 may connect R2 intermittently or continuously to a vacuum source. Ideally, the pressure of the incoming mixture is reduced to such a level that the boiling temperature of isomerized yet unreacted feed (under reduced pressure), matches the reaction temperature used in Rl, thus minimizing heating cooling requirements in the process.

[0041] Rl temperature is maintained at a minimum temperature (e.g., 90 °C or below) such that sufficient dimerization (5-80%) takes place before exiting the Rl device. The heat generated in Rl is distributed in the jacket in such a manner that the length of catalyst in Rl is maintained at relatively constant temperature throughout the length of the catalyst bed. The instant result of this invention utilizes heat generated in Rl to heat R2 to an optimum reaction temperature. The optimum reaction temperature is one which obtains sufficient (5-80%) dimerization formation in a single pass through Rl and R2) and remaining at or below a selected minimum temperature, such as 90 °C. The length of Rl and/or flow rate through the reactor can also be modified to obtain sufficient dimerization reaction in a single pass and maintain a temperature of 90 ° C or less. Reduced pressure can be applied to R2 such that the olefin reactant will boil at or slightly below the optimum reaction temperature used in Rl and thus matches the reaction temperature used in Rl. One skilled in the art of distillation can preselect the reduced pressure necessary to match the distillation temperature to the optimum reaction temperature in Rl for an olefin reactant.

[0042] A fluid flow path 12 connects R2 to Rl to return the evaporated unconverted/isomerized (but typically not dimerized or oligomerized) olefin as a feedstock. The bottoms from R2 are the dimer and, as stated above, reaction temperature and reaction times should be optimized to afford a product with less than 5 wt. % oligomers (e.g. trimer and tetramer), and in some embodiments, no more than 2 wt. % or no more than 1 wt. % of such oligomers. The recycling process can be continued until all the feed it converted to dimeric product with no more than 5 wt. % trimer and higher oligomeric products and more typical of this invention is less than 1 wt. %.

[0043] The dimers produced in embodiments of the invention are converted to diesel and turbine fuels with a flash point greater than 61 °C by addition to the system of a third reactor that is capable of carrying out hydrogenation so the dimer products become fully saturated hydrocarbons. FIG. 2 shows the addition of a third reactor R3 which can be a trickle bed reactor or a fixed volume reaction vessel provided with mechanical stirring. Typical catalysts for the hydrogenations could include, but are not limited to, palladium, platinum, or nickel supported on various solid supports including amorphous carbon, and in particular for nickel, aluminum (e.g. Raney-Nickel®). Typical sources of hydrogen can be from the thermal cracking of biomass including, but not limited to, lignin or through hydrogen-producing bacteria that is pressurized to meet the reaction requirements, typically in the range of about 50 to about 2000 psig (about 446-1389 kpa).

[0044] Addition of a hydrocracking reactor to the process and apparatus provides a method for reducing the molecular weight of the dimeric products while providing a broader distribution of molecular weights which can be considered beneficial for diesel or turbine fuels although not a requirement. As the dimers formed in embodiments of the invention are significantly branched, mild hydrocracking can be used or as those practiced in the art would refer to it as light cracking or light reforming processes. FIG. 3 shows the addition of the hydrocracking reactor R4 and depending on the desired biofuel characteristics, some fractionation may be required to provide sufficient flash point and cold flow properties. A suitable hydrogenation and/or hydrocracking reagent , such as hydrogen, can be introduced to reactor R3 and/or R4 via flowpath(s) 34. A final fractionator 38 can be used in the process as shown in FIG. 3.

[0045] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

Claims

CLAIMS What is Claimed is:

1. A dimerization process, comprising:

introducing at least one oligomer-based feedstock which includes an olefin selected from the group consisting of terpenes, alpha-olefin oligomers (AOO), and related olefins;

introducing at least one solid acid catalyst to said feedstock for isomerization;

recovering and utilizing the initial heat of said isomerization;

utilizing a first fractionation process for the evaporation of unreacted feedstock, the first fractionation process reducing a pressure of the unreacted feedstock,

adjusting the concentration of reacting olefin during the isomerization via an active recycle protocol which produces dimerized products and suppresses formation of oligomers of the olefin, enabling utilizing a lowered reaction temperature during the isomerization to extend the lifetime of the catalyst, and producing a purer dimerized product having less than 5 wt. %, or less than 2 wt. %, or less than 1 wt. % in total of the oligomers of the olefin combined.

2. The process according to claim 1, further characterized by initially diluting of said feedstock or olefin.

3. The process according to claim 1, further characterized by at least one said terpene being selected from the group consisting of monoterpenes, sesquiterpenes, diterpenes, terpenes being linear or having more than one ring, terpenes having at least one site being unsaturated, terpenes having at least one double bond that can be hydrogenated, and C₅ to C₃₀ terpenes.

4. The process according to claim 1, further characterized by at least one said terpene being at least one of acyclic and cyclic, wherein acyclic terpenes include famesene and cyclic terpenes include limonene.

5. The process according to claim 1, further characterized by said AOO including at least one C₆ to C₂8 AOO.

6. The process according to claim 1, further characterized by said AOO comprising bio-2-ethyl-l -hexene.

7. The process according to claim 1, further characterized by said active recycle protocol being performed by diluting said feedstock with recycled and isomerized olefins.

8. The process according to claim 1, further characterized by said first fraction process comprising evaporating with an evaporator selected from the group consisting of at least one wiped film evaporator, a thin film evaporator, and other flash type distillation operations.

9. The process according to claim 1, further characterized by said first fraction process being performed with more than one column.

10. The process according to claim 1, further characterized by said first fraction process product being recycled into said protonation/dimerization process for complete conversion to dimer products.

1 1. The process according to claim 1, comprising, prior to said first fractionation process, monitoring with a monitoring system to detect for presence of oligomers.

12. The process according to claim 1, further characterized by said reducing pressure during said first fractionation process comprising reducing pressure to such a level that the boiling temperature of isomerized yet non-dimerized feedstock matches a target temperature of said protonation/dimerization process.

13. The process according to claim 1, further characterized by processing said dimerized product through hydrogenation to produce fully saturated hydrocarbon dimer products that can be directly placed in use as diesel and jet/turbine fuels with a flashpoint greater than 61.

14. The process according to claim 13, further characterized by said hydrogenation process being selected from the group consisting of at least one trickle bed reactor and/or fixed volume reaction vessel with mechanical stirring.

15. The process according to claim 13, further characterized by introducing at least one catalyst into said hydrogenation process.

16. The process according to claim 15, further characterized by said at least one catalyst being transition metals selected from the group palladium, platinum, nickel, and any combination thereof.

17. The process according to claim 13, further characterized by processing said fully saturated hydrocarbon dimer products through a hydrocracking reactor process to reduce the molecular weight of said saturated hydrocarbon dimer products and/or to produce a lower boiling fuel product.

18. The process according to claim 17, further characterized by introducing at least one catalyst into said hydrocracking process.

19. The process according to claim 18, further characterized by said at least one catalyst for said hydrocracking process being selected from the group consisting of palladium, platinum, nickel, and combinations thereof, supported on a high surface substrates selected from the group consisting of silicate, aluminate, zeolite, and other mesoporous inorganic supports.

20. The process according to claim 17, further characterized by introducing at least one reagent into at least one of said hydrogenation process and said hydrocracking process.

21. The process according to claim 20, further characterized by said at least one reagent including ¾.

22. The process according to claim 17, further characterized by processing said lower boiling fuel product through a second fractionation process to product a fully saturated hydrocarbon biofuel with sufficient flashpoint and cold flow properties.

23. The process according to claim 17, further characterized by the oligomers of the olefin being selected from the group consisting of trimers, tetramers, and up to octamers of the olefin.

24. A dimer product having no more than 2 wt. % combined total mass of trimer, tetramer, and other oligomers of said olefin produced by the process of any one of claims 1- 23.

25. The dimer product of claim 24 having no more than 1 wt. % combined total mass of trimer, tetramer, and other oligomers of said olefin produced by the process of any one of claims 1 -23.

26. A fully saturated hydrocarbon gas, diesel, jet/turbine biofuel produced by the process of claim 22 or 23.

27. A dimerization system for converting olefins into dimer products, comprising: a source (10) of at least one feedstock comprising an olefin selected from the group consisting of terpene(s), alpha-olefin oligomer(s), and related olefins;

a first reactor (Rl) in which at least one solid acid catalyst is contacted with said feedstock for isomerization by protonation; a heat collector (20) for recovering and utilizing the initial heat of said isomerization; a second reactor (R2) configured for performing a first fractionation process which separates unreacted olefin from a fluid mixture exiting from the first reactor, the second reactor having an outlet (14) for reducing pressure of the fluid mixture;

a recycle flow path (12) which returns the separated olefin from the second reactor (R2) to the first reactor (Rl) to adjust the concentration of reacting olefin during the protonation, which enables lowering reaction temperature in the first reactor (Rl) to extend the catalyst lifetime and decreasing oligomer formations, to produce dimerized products of the olefin with reduced concentrations of oligomers of the olefin.

28. The system of claim 27, further characterized by the dimerized product having less than 5 wt. %, or less than 2 wt. %, or less than 1 wt. % in total of trimers and other oligomers of the olefin combined.

29. The system according to claim 27, further characterized by a valve (VI) for adding diluents to initially dilute said feedstock and/or olefin.

30. The system according to claim 27, further characterized by at least one said terpene being selected from the group consisting of monoterpenes, sesquiterpenes, diterpenes, terpenes being linear or having more than one ring, terpenes having at least one site being unsaturated, terpenes having at least one double bond that can be hydrogenated, and terpenes having from 5 to 30 carbons.

31. The system according to claim 27, further characterized by at least one said terpene being acyclic, including farnesene, and/or cyclic, including limonene.

32. The system according to claim 27, further characterized by the alpha-olefin oligomer comprising at least one C₆ to about C₂₈ poly-alpha-olefin.

33. The system according to claim 27, further characterized by at least one said AOO comprising bio-2-ethyl-l-hexene.

34. The system according to claim 27, further characterized by diluting said feedstock with said recycled and isomerized olefins.

35. The system according to claim 27, further characterized by said second reactor comprising at least one evaporator selected from the group consisting of at least one wiped film evaporator, a thin film evaporator, and other flash type distillation systems.

36. The system according to claim 27, further characterized by said second reactor including more than one column.

37. The system according to claim 27, further characterized by said first fraction being recycled into said protonation/dimerization process for complete conversion to dimer products.

38. The system according to claim 27, further characterized by a monitor system (24) prior to said first fractionation process to detect for presence of oligomers in said exiting fluid.

39. The system according to claim 27, further characterized by said second reactor including an outlet (14) to reduce pressure to such a level that the boiling temperature of isomerized yet non-dimerized feedstock matches a target temperature of said protonation/dimerization process.

40. The system according to claim 27, further characterized by a hydrogenation device (R3) to produce fully saturated hydrocarbon dimer products that can be directly placed in use as diesel and jet/turbine fuels with a flashpoint greater than 61 °C.

41. The system according to claim 40, further characterized by said hydrogenation device being selected from the group consisting of at least one trickle bed reactor and a fixed volume reaction vessel with mechanical stirring.

42. The system according to claim 40, further characterized by the hydrogenation device comprising at least one catalyst.

43. The system according to claim 42, further characterized by the at least one catalyst for the hydrogenation device comprising a transition metal selected from the group consisting of palladium, platinum, nickel, and combinations thereof.

44. The system according to claim 40, further characterized by a hydrocracking reactor (R4) to reduce the molecular weight of said saturated hydrocarbon dimer products and/or to produce a lower boiling fuel product from said fully saturated hydrocarbon dimer products.

45. The system according to claim 44, further characterized by said hydrocracking reactor comprising at least one catalyst.

46. The system according to claim 45, further characterized by said at least one catalyst for hydrocracking being selected from the group consisting of palladium, platinum, nickel and combinations thereof and is supported on a high surface substrates selected from the group consisting of silicate, aluminate, zeolite, and mesoporous inorganic supports.

47. The system according to claim 44, further characterized by means (30) for introducing at least one reagent into at least one of said hydrogenation reactor and said hydrocracking device.

48. The system according to claim 47, further characterized by said reagent including

H₂.

49. The system according to claim 44, further characterized by a second fractionation reactor (R4) to product a fully saturated hydrocarbon biofuel with sufficient flashpoint and cold flow properties from said lower boiling fuel product.

50. A dimerized product from oligomers, comprising:

at least one oligomer-based composition or feedstock selected from the group consisting of terpene(s), alpha-olefin oligomer(s) (AOO), and related olefins;

at least one solid acid catalyst to said feedstock for isomerization, further characterized by said oligomer-based composition or feedstock and said catalyst are converted into a dimerized product having less than 2 wt% total oligomers by processes of isomerization utilizing heat, protonation:

maximizing the concentration of reacting olefin during protonation;

utilizing a minimum reaction temperature zone to extend said catalyst lifetime;

decreasing trimer and oligomer formations via an active recycle protocol to produce dimerized products in the absence of trimeric, tetrameric, and up to octameric; and

utilizing a first fractionation process that mildly reduces pressure for the evaporation of unreacted feedstock to produce a dimerized product.

51. A saturated hydrocarbon biofuel, formed by a process comprising:

maximizing the concentration of reacting olefin during protonation;

utilizing a minimum reaction temperature zone to extend said catalyst lifetime;

decreasing trimer and oligomer formations via an active recycle protocol to produce dimerized products in the absence of trimeric, tetrameric, and up to octameric;

utilizing a first fractionation process that mildly reduces pressure for the evaporation of unreacted feedstock to produce a dimerized product;

a hydrogenation system/device to produce fully saturated hydrocarbon dimer products from said either dimerized product;

at least one catalyst into said hydrogenation process; a hydrocracking reactor system/device to reduce the molecular weight of said saturated hydrocarbon dimer products and/or to produce a lower boiling fuel product from said fully saturated hydrocarbon dimer products;

at least one catalyst into said hydrocracking process;

at least one reagent which is introduced into said hydrogenation process and said hydrocracking process; and

a second fractionation process to product a fully saturated hydrocarbon biofuel with sufficient flashpoint and cold flow properties from said lower boiling fuel product.

52. The biofuels according to claim 51, further characterized by diluents to initially dilute said feedstock(s)/oligomer(s).

53. The biofuel according to claim 51, further characterized by at least one said terpene is selected from the group consisting of monoterpenes, sesquiterpenes, diterpenes, terpenes being linear or having more than one ring, terpenes having at least one site being unsaturated, terpenes having at least one double bond that can be hydrogenated, and terpenes having from about C₅ to about C₃₀ carbons.

54. The biofuel according to claim 51, further characterized by at least one said terpene is acyclic including farnesene and/or cyclic including limonene.

55. The biofuel according to claim 51, further characterized by at least one said alpha-olefin oligomer has about C₆ to about C₂8 carbons.

56. The biofuels according to claim 51, further characterized by at least one said alpha-olefin oligomer comprises bio-2-ethyl-l-hexene.

57. The biofuels according to claim 51, further characterized by said active recycle protocol being performed by diluting said feedstock with said recycled and isomerized olefins.

58. The biofuels according to claim 51 , further characterized by said first fraction process comprising at least one evaporator selected from the group consisting of at least one wiped film evaporator, thin film evaporator, and other flash type distillation operation.

59. The biofuels according to claim 51, further characterized by said first fraction process including more than one column.

60. The biofuels according to claim 51, further characterized by said first fraction process being recycled into said protonation process to convert into a more concentration of dimers.

61. The biofuels according to claim 51, further characterized by a monitor system/device being utilized prior to said first fractionation process to detect for presence of oligomers.

62. The biofuels according to claim 51, further characterized by said first fractionation process being to reduce pressure to such a level that the boiling temperature of isomerized yet non-dimerized feedstock matches the target temperature of said protonation/dimerization process.

63. The biofuels according to claim 51, further characterized by said hydrogenation system/device being selected from the group consisting of at least one trickle bed reactor and/or fixed volume reaction vessel with mechanical stirring.

64. The biofuels according to claim 51, further characterized by said at least one catalyst being a transition metal selected from the group consisting of palladium, platinum, nickel, and combinations thereof.

65. The biofuels according to claim 51, further characterized by said reagent includes