WO2015198268A1

WO2015198268A1 - Processes and systems for preparing glycerol tert-butyl ethers from glycerol and isobutylene

Info

Publication number: WO2015198268A1
Application number: PCT/IB2015/054794
Authority: WO
Inventors: Christoph DITTRICH; Luis ARAMBURO
Original assignee: Sabic Global Technologies B.V.
Priority date: 2014-06-27
Filing date: 2015-06-25
Publication date: 2015-12-30

Abstract

A process for generating a glycerol tert-butyl ether is provided. The process includes feeding glycerol and isobutylene into a reactor and reacting glycerol with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction. The reactor includes an acid catalyst, and the reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase. Additional processes and systems for generating glycerol tert-butyl ethers are also provided.

Description

PROCESSES AND SYSTEMS FOR PREPARING GLYCEROL TERT-BUTYL ETHERS FROM GLYCEROL AND ISOBUTYLENE

TECHNICAL FIELD

[0001] The presently disclosed subject matter relates to processes and systems for generating glycerol tert-butyl ethers from glycerol and isobutylene.

BACKGROUND

[0002] Glycerol, also known as glycerin or glycerine, is a colorless, odorless, viscous liquid. Glycerol has various uses, including, for example, as an antifreeze agent and as an excipient in certain pharmaceutical preparations. Glycerol occurs in nature and can also be prepared synthetically by various routes. Among the sources of glycerol is commercial production of biodiesel. Glycerol can be a waste product in the generation of biodiesel

[0003] Biodiesel is a fuel or component of fuel that can be used for various purposes, including powering diesel motors. Biodiesel has received attention as a renewable fuel and can be a complement to and/or substitute for various fossil fuels. Biodiesel is typically a mixture of chemical compounds, including alkyl esters of natural fatty acids, and can be generated through the transesterification of triglycerides with simple alcohols in the presence of a catalyst. Such transesterification reactions can generate alkyl esters of fatty acids along with glycerol as a byproduct.

[0004] Biodiesel fuels can be mixed with various additives, including glycerol ethers. Glycerol ethers are ether compounds herein at least one of the carbon moieties attached to an ether linkage is derived from glycerol. Glycerol ethers can be derived from renewable sources and are accordingly of interest as a renewable source of energy. Glycerol ethers can be added to gasoline, diesel, biodiesel, and other fuels and can impart various desirable properties to the fuel. For example, glycerol ethers can be added to fuels as an oxygenate to improve the performance of the fuels. Glycerol ethers can be soluble in various fuels, including biodiesel, and otherwise compatible with the fuels.

[0005] As glycerol is a triol and has three hydroxyl groups capable of derivatization into ether linkages, glycerol ethers include mono-, di-, and tri-ether compounds. Examples of glycerol ethers include glycerol tert-butyl ethers (GTBEs). Five structurally distinct glycerol tert-butyl ethers can be formed: (1) 1-tert-butyl glycerol (3-(tert-butoxy)propane-l ,2-diol); (2) 2-tert-butyl glycerol (2-(tert-butoxy)propane-l,3-diol); (3) 1 ,3-di-tert-butyl glycerol (1,3- di-(tert-butoxy)propan-2-ol); (4) 1 ,2-di-tert-butyl glycerol (l,2-di-(tert-butoxy)propan-3-ol); and (5) tri-tert-butyl glycerol (l,2,3-tri-(tert-butoxy)propane). The first two compounds, 1- tert-butyl glycerol and 2-tert-butyl glycerol, are mono-tert-butyl glycerol ethers (mono- GTBEs, also known as m-GTBEs). The next two compounds, 1,3-di-tert-butyl glycerol and 1 ,2-di-tert-butyl glycerol, are di-tert-butyl glycerol ethers (di-GTBEs). The last compound, tri-tert-butyl glycerol, is tri-tert-butyl glycerol ether (tri-GTBE, also known as t-GTBE). Di- GTBEs and tri-GTBEs are sometimes known together as higher GTBEs, or h-GTBEs.

[0006] GTBEs can have useful properties as fuel additives, particularly as compared to certain existing additives. For example, methyl tert-butyl ether (MTBE) is soluble in diesel, biodiesel, and other fuels and is a commonly used oxygenate fuel additive. However, MTBE has relatively high water solubility and can cause hazardous water contamination. Like MTBE, GTBEs can be soluble in diesel, biodiesel, and other fuels and can be used as oxygenate fuel additives. For example, di-GTBEs and tri-GTBE are desirable as fuel additives, as they have good solubility in diesel and biodiesel fuels. However, unlike MTBE, di-GTBEs and tri-GTBEs have low solubility in water, which makes them less likely to cause water contamination.

[0007] Glycerol ethers can also be appealing because they can be generated from glycerol, which, as noted above, is often a byproduct of biodiesel production. Glycerol ether formation can accordingly convert a relatively low value compound (glycerol) into a useful product (glycerol ethers).

[0008] Certain existing processes of generating glycerol tert-butyl ethers (GTBEs) involve etherification reactions of glycerol with tert-butyl alcohol (TBA). Etherification reactions of glycerol with tert-butyl alcohol can suffer from certain drawbacks. For example, generation of GTBEs from the etherification of reaction of glycerol with TBA releases water, which can deactivate the acidic catalysts often used in such etherification reactions. Other existing processes of generating GTBEs can involve etherification reactions of glycerol and isobutylene. Etherification reactions of glycerol with isobutylene under standard conditions can also suffer from certain drawbacks. For example, etherification of glycerol with isobutylene can suffer from mass transfer limitations caused by a non-optimal contact between isobutylene and glycerol liquid phases. Other drawbacks with etherification of glycerol with isobutylene can include undesired secondary reactions (e.g., oligomerization of isobutylene), poor control of product selectivity (e.g., poor control of the relative output of m- GTBEs, di-GTBEs, and tri-GTBE), and limited catalyst lifetime. [0009] Thus, there remains a need in the art for improved processes and systems for generating glycerol tert-butyl ethers with improved properties, including improved economy, efficiency, and selectivity.

SUMMARY

[0010] The presently disclosed subject matter provides processes and systems for generating glycerol tert-butyl ethers.

[0011] A process for generating a glycerol tert-butyl ether, comprises: feeding glycerol and isobutylene into a reactor; and reacting glycerol with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction, wherein: the reactor comprises an acid catalyst; and the reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase.

[0012] A process for generating a glycerol tert-butyl ether, comprises: feeding glycerol and isobutylene into a first reactor; reacting glycerol with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction, wherein: the first reactor comprises an acid catalyst; and the first reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase; removing a liquid reaction mixture from the first reactor; feeding the liquid reaction mixture into a second reactor; and reacting glycerol in the liquid reaction mixture with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction, wherein: the second reactor comprises an acid catalyst; and the second reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase.

[0013] A system for generating a glycerol tert-butyl ether using an acid catalyst, comprises: a reactor configured to receive the acid catalyst; an isobutylene teed coupled to the reactor for supplying isobutylene thereto; and a glycerol feed coupled to the reactor for supplying glycerol thereto, wherein: the reactor is adapted to operate at a temperature and a pressure at which the isobutylene is in a gaseous phase and the glycerol is in a liquid phase.

[0014] A system for generating a glycerol tert-butyl ether using acid catalysts, comprises: a first reactor configured to receive a first acid catalyst, an isobutylene feed coupled to the first reactor for supplying isobutylene thereto; a glycerol feed coupled to the first reactor for supplying glycerol thereto; an overhead system coupled to the first reactor for receiving gaseous isobutylene from the first reactor; and a second reactor configured to receive a second acid catalyst coupled to the overhead system for receiving an isobutylene feed from the overhead system and further coupled to the first reactor for receiving a liquid feed from the first reactor.

[0015] These and other features and characteristics are more particularly described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0001] The following is a brief description of the drawings wherein like elements are numbered alike and which are presented for the purposes of illustrating the exemplary embodiments disclosed herein and not for the purposes of limiting the same.

[0002] FIG. 1 is a schematic diagram showing an exemplary system for generating a glycerol tert-butyl ether in accordance with one non-limiting embodiment of the disclosed subject matter.

DETAILED DESCRIPTION

[0003] The presently disclosed subject matter provides processes and systems for generating glycerol tert-butyl ethers.

[0004] In one non-limiting embodiment, an exemplary process for generating a glycerol tert- butyl ether includes feeding glycerol and isobutylene into a reactor and reacting glycerol with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction. The reactor includes an acid catalyst, and the reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase.

[0005] In certain embodiments, a solvent can be fed into the reactor with glycerol and isobutylene. The solvent can be one or more solvents selected from tetrahydrofuran (THF), mono-tert-butyl glycerol ether, or a combination comprising at least one of the foregoing.

[0006] In certain embodiments, isobutylene can be fed into the reactor as part of a mixed C4 stream. In certain embodiments, isobutylene can be fed into the reactor in a liquid phase and can be converted to a gaseous phase in the reactor.

[0007] In another non-limiting embodiment, an exemplary process for generating a glycerol tert-butyl ether includes feeding glycerol and isobutylene into a first reactor and reacting glycerol with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction. The first reactor includes an acid catalyst, and the first reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase. The exemplary process can further include removing a liquid reaction mixture from the first reactor, feeding the liquid reaction mixture into a second reactor, and reacting glycerol in the liquid reaction mixture with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction. The second reactor includes an acid catalyst and the second reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase.

[0008] In certain embodiments, the first reactor and the second reactor can be configured at different temperatures and pressures. The concentration of isobutylene in the first reactor can be lower than the concentration of isobutylene in the second reactor.

[0009] In certain embodiments, the process for generating a glycerol tert-butyl ether can further include removing a second liquid reaction mixture from the second reactor, feeding the second liquid reaction mixture into a third reactor, and reacting glycerol in the second liquid reaction mixture with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction. In such embodiments, the third reactor can include an acid catalyst, and the third reactor can be configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase. The temperature and pressure of the first reactor, the second reactor, and the third reactor can each be configured at different temperatures and pressures. The concentration of isobutylene in the first reactor can be lower than the concentration of isobutylene in the second reactor, and the concentration of isobutylene in the second reactor can be lower than the concentration of isobutylene in the third reactor.

[0010] In certain embodiments, the first reactor can include an acid catalyst different from the acid catalyst of the second reactor.

[0011] In certain embodiments, a solvent can be fed into the first reactor with glycerol. The solvent can be one or more solvents selected from THF, mono-tert- butyl glycerol ether, or a combination comprising at least one of the foregoing.

[0012] In certain embodiments, isobutylene can be fed into the reactor as part of a mixed C4 stream.

[0013] In certain embodiments, isobutylene can be fed into the reactor in a liquid phase and can be converted to a gaseous phase in the reactor.

[0014] In one non-limiting embodiment, an exemplary system for generating a glycerol tert-butyl ether using an acid catalyst includes a reactor configured to receive the acid catalyst, an isobutylene feed coupled to the reactor for supplying isobutylene thereto, and a glycerol feed coupled to the reactor for the supplying glycerol thereto. The reactor is adapted to operate at a temperature and a pressure at which the isobutylene is in a gaseous phase and the glycerol is in a liquid phase. [0015] In one non-limiting embodiment, an exemplary system for generating a glycerol tert-butyl ether using acid catalysts includes a first reactor configured to receive a first acid catalyst, an isobutylene feed coupled to the first reactor for supplying isobutylene thereto, a glycerol feed coupled to the first reactor for supplying glycerol thereto, an overhead system coupled to the first reactor for receiving gaseous isobutylene from the first reactor, and a second reactor configured to receive a second acid catalyst coupled to the overhead system for receiving an isobutylene feed from the overhead system and further coupled to the first reactor for receiving a liquid feed from the first reactor.

[0016] In certain embodiments, the first reactor can be adapted to operate at a first temperature and a first pressure and the second reactor can be adapted to operate at a second temperature and a second pressure. The first temperature and the first pressure can be different from the second temperature and the second pressure.

[0017] In certain embodiments, the first acid catalyst can be different from the second acid catalyst.

[0018] The processes and systems of the present disclosure involve use of one or more reactors. The reactor can be of various designs known in the art, e.g., a continuously stirred tank reactor (CSTR), a mechanically stirred tank reactor, a trickle-flow fixed bed reactor, a bubble column reactor (BCR), or any other kind of reactor desirable for gas/liquid reactions. In certain embodiments, the reactor is a bubble column reactor. The bubble column reactor can be a slurry bubble column reactor. The reactor can be constructed of any desirable materials such as, but not limited to, metals, alloys (including steel), glasses, enamels, ceramics, polymers, plastics, or a combination comprising at least one of the foregoing. The reactor can include a reaction vessel enclosing a reaction chamber.

[0019] The reaction vessel can be any desirable design or shape such as, but not limited to, tubular, cylindrical (as shown in FIG. 1), rectangular, dome, or bell-shaped. The dimensions size of the reaction vessel and reaction chamber are variable and can depend on the desired reaction type, production capacity, feed volume, and catalyst. For example, the reactor size can be up to about 20,000 liters (L) (e.g., for commercial reactors). The reactor can include various components. For example, the reactor can optionally include one or more gas spargers to introduce a gas (e.g., isobutylene) to the reaction chamber. The reactor can optionally include an external jacket mounted on or in proximity to the reactor, to heat or cool all or a portion of the reaction chamber. The reactor can optionally include a tray on which a catalyst, e.g. a solid acid catalyst, is positioned. The geometries of the reactor and of the overall systems for generating glycerol tert-butyl ethers are adjustable in various ways known to one of ordinary skill in the art.

[0020] The reactor can be selected to optimize mixing of the liquid and gaseous phases within the reaction vessel. The reactor can be selected to optimize the interface area (surface area) between the liquid and gaseous phases.

[0021] In certain embodiments, the reactor can be selected to enable a residence time of the liquid phase or phases of about 3 to about 5 minutes to about 3 to about 5 hours. The residence time can be optimized by adjustment of various reactor parameters, e.g., flow rates of inputs into the reactor and/or outputs out of the reactor.

[0022] As noted above, glycerol is a colorless liquid at ambient conditions (room temperature and atmospheric pressure). Glycerol has a boiling point of 290°C at atmospheric pressure. Room temperature as described herein generally refers to a temperature of about 21°C and atmospheric pressure refers to a pressure of 1 atmosphere (atm) (101.3 kiloPascals (kPa)).

[0023] The glycerol used as an input to generate glycerol tert-butyl ethers can be high purity glycerol, but the processes and systems for generating glycerol tert-butyl ethers of the present disclosure do not require the use of high purity glycerol. The etherification reaction of the present disclosure can tolerate glycerol that is contaminated with some amount of methanol and/or water. Accordingly, the processes and systems of the present disclosure can permit use of lower purity (and lower cost) glycerol than existing processes and systems that require high purity glycerol.

[0024] Isobutylene is a simple olefin (alkene) compound also known as 2- methylpropene, isobutene, gamma-butylene, 2-methylpropylene, methylpropene, and 2- methyl-l-propene. Isobutylene is a gas at ambient conditions (room temperature and atmospheric pressure) and has a boiling point of -6.9°C at atmospheric pressure. At certain temperatures and pressures, isobutylene may be in a gaseous (vapor) phase. When in the gaseous phase, isobutylene can have a solubility in a liquid phase. The solubility of isobutylene gas in a liquid phase is dependent on the temperature and pressure of the liquid and gas phases.

[0025] The isobutylene used as an input to generate glycerol tert-butyl ethers can be high purity isobutylene, but the processes and systems for generating glycerol tert-butyl ethers of the present disclosure do not require the use of high purity isobutylene. In certain embodiments of the presently disclosed subject matter, relatively low purity isobutylene can be used. For example, isobutylene can be fed into the reactor as part of a mixed C4 stream. The mixed C4 stream can contain various C4 hydrocarbons other than isobutylene, e.g., n- butane, isobutane, and/or n-butenes. In certain embodiments, n-butane, isobutane, and n- butenes do not react under the conditions of the presently disclosed processes for generating glycerol tert-butyl ethers and accordingly do not interfere with the formation of glycerol tert- butyl ethers. Mixed C4 streams are readily and inexpensively available, e.g., as products of olefin plants. Accordingly, the disclosed subject matter provides low-cost processes and systems for generating glycerol tert- butyl ethers.

[0026] In certain embodiments of the presently disclosed processes and systems for generating glycerol tert-butyl ethers, a solvent can be fed into one or more of the reactors, along with glycerol. The solvent can then help to dissolve various components of the etherification reaction - the glycerol and isobutylene starting materials as well as the etherification products, mono-, di-, and tri-GTBEs.

[0027] Because glycerol and isobutylene are immiscible, etherification reactions of glycerol and isobutylene can involve two distinct liquid phases: a relatively polar phase rich in glycerol and a relatively nonpolar phase rich in isobutylene. The existence of two distinct, immiscible liquid phases can imply non-intimate contact between the phases, which can limit mass transfer. Limited mass transfer can in turn reduce reaction rate and can, in some cases, accelerate undesired side reactions. Examples of undesired side reactions in etherification reactions of glycerol and isobutylene can include oligomerization of isobutylene, disproportionation reactions of the glycerol ether products (GTBEs), and decomposition reactions of the GTBEs.

[0028] Addition of a solvent to the etherification reaction of glycerol and isobutylene can render both glycerol and isobutylene soluble in a single, homogenous liquid phase. Accordingly, addition of a solvent can, in some cases, improve mass transfer, improve reaction rate, and reduce side reactions. The solvent can be a compound that is liquid under the etherification reaction conditions and that possesses a polarity intermediate between that of relatively polar glycerol and relatively nonpolar isobutylene. For example, the solvent can be an ether. In certain non-limiting embodiments, the solvent can be selected from the group consisting of tetrahydrofuran (THF) and mono-tert-butyl glycerol ethers (mono-GTBEs).

[0029] If one or more mono-tert-butyl glycerol ethers are used as a solvent, then the solvent is a reactive solvent; that is, the solvent is also a product of the etherification reaction of glycerol and isobutylene and also a reactant that can react with isobutylene to form di- GTBEs. In certain embodiments, mono-GTBEs can be formed as products of the processes and systems of the present disclosure, separated from other products (e.g., di-GTBEs and/or tri-GTBEs), and then recycled back into one or more reactor for use as a solvent and as a reactant for further reaction.

[0030] If tetrahydrofuran (THF) is used as a solvent, then the solvent has a boiling point substantially higher than that of isobutylene and other C4 hydrocarbons but substantially lower than that of glycerol Tetrahydrofuran has a boiling point of 66°C at ambient pressure. Ambient pressure generally refers to the pressure of the surrounding medium of an object, such as a gas or liquid that comes into contact with the object. Because of the substantial differences in boiling point, tetrahydrofuran can easily be removed from the reaction or product mixture by distillation. Tetrahydrofuran can also be a useful solvent because it can be unreactive under the etherification reaction conditions and avoid interference with generation of glycerol tert-butyl ethers.

[0031] In certain embodiments, when a solvent is used, the solvent can be added to the reactor as a mixture with glycerol. The solvent can be pre-mixed with glycerol and added with the glycerol feed. In certain embodiments, the solvent can be added to the reactor separately from the glycerol feed.

[0032] The etherification reactions of the presently disclosed processes and systems for generating glycerol tert-butyl ethers can involve a catalyst. The catalyst can be a homogenous catalyst, a heterogeneous catalyst, or a combination comprising at least one of the foregoing. The catalyst can be an acid catalyst. The acid catalyst can be a Bronsted acid and/or a Lewis acid. Examples of suitable catalysts for the etherification of glycerol and isobutylene to generate GTBEs include, but are not limited to, molecular sieves (e.g., 4A molecular sieves), ion-exchange resins (e.g., AMBERLYST™ resins and AMBERLITE™ resins), sulfuric acid, acetic acid, formic acid, hydrochloric acid, sulfamic acid,

methanesulfonic acid, phosphoric acid, trifluoroacetic acid, and other catalysts known to one of ordinary skill in the art to be capable of catalyzing etherification reactions as well as a combination comprising at least one of the foregoing. One or more catalysts can be used in a single reactor.

[0033] Heterogeneous catalysts can be used as solid particulates dispersed in a liquid phase. Alternatively, heterogeneous catalysts can be immobilized on a solid support.

Examples of solid supports used to prepare immobilized heterogeneous catalysts can include various metal salts, metalloid oxides, and metal oxides, e.g., titanium oxide, zirconium oxide, silica (silicon oxide), alumina (aluminum oxide), magnesium oxide, and magnesium chloride. In certain embodiments, the solid support can be chosen for its high surface area. [0034] In certain embodiments of the presently disclosed processes and systems that involve the use of more than one reactor, each reactor can include catalysts that are the same or different. For example, in certain embodiments with two reactors, the first reactor can include a catalyst different from the catalyst of the second reactor. Heterogeneous catalysts immobilized on a solid support can be used to prevent catalysts from passing from one reactor into another. The choice of catalyst in each reactor can depend on the properties desired. For example, a cheaper catalyst can be included in the first reactor, where glycerol is first introduced, and a more expensive catalyst can be included in the second reactor. The cheaper catalyst can be poisoned or degraded by methanol, water, or other impurities in the glycerol. The cheaper catalyst can be replaced periodically. In this way, the cheaper catalyst can serve as a "sacrificial" catalyst that consumes methanol, water, and/or other impurities in the reaction mixture. In certain embodiments, molecular sieves can be added to the first reactor to trap methanol and/or water, thereby slowing catalyst degradation. In certain embodiments, ion-exchange resins can be added to the first reactor to remove particular ionic impurities, thereby slowing catalyst degradation.

[0035] Because methanol, water, and other impurities can be consumed by a cheaper catalyst in a first reactor, the lifetime of a more expensive catalyst in a second or subsequent reactor in a series can be extended. Expensive catalysts that have desirable properties- e.g., high selectivity for di-GTBEs and tri-GTBEs over mono-GIBEs, high reaction rate, and/or low levels of side reactions - can be included in the second and subsequent reactors while degradation of these catalysts by methanol, water, and other impurities is minimized. In this way the lifetime of the expensive catalysts is extended and the overall economy of the processes and systems can be improved.

[0036] By way of non-limiting example, the etherification reaction of glycerol and isobutylene can be performed with a catalyst loading of about 0.01% to about 25%, by weight, as compared to the weight of glycerol. In certain embodiments, the reaction can be performed with a catalyst loading of about 0.1% to about 10%, by weight, as compared to the weight of glycerol.

[0037] The presently disclosed subject matter provides processes and systems for generating glycerol tert-butyl ethers through etherification reactions of glycerol and isobutylene. The etherification reactions can be conducted at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase. The etherification reactions can be conducted at temperatures and pressures known in the art. For example, in certain non-limiting embodiments, the reactions can be conducted at a temperature of about 40°C to about 120°C and at a pressure of about 2 bar to about 20 bar (about 200 kPa to about 2000 kPa). In certain embodiments, the reactions can be conducted at a temperature of about 60°C to about 90°C and at a pressure of about 3 bar to about 15 bar (about 300 kPa to about 1500 kPa).

[0038] The etherification reactions of the present disclosure involve isobutylene in a gaseous phase and glycerol in a liquid phase. As the etherification reaction proceeds, quantities of mono-GTBEs, di-GTBEs, and tri-GTBE will be formed. These GTBEs will also be present in the liquid phase. There can be two immiscible liquid phases, one a relatively polar phase rich in glycerol and one a relatively nonpolar phase rich in isobutylene. The relatively nonpolar phase can also contain GTBEs, especially the relatively nonpolar di- and tri-GTBEs. By configuring the temperature and pressure of the reactor, the concentration of isobutylene soluble in the liquid phase(s) can be predetermined and controlled. Because the solubility of isobutylene in a liquid phase is primarily dependent on the temperature and pressure of the system rather than the volume of isobutylene gas, a large excess of isobutylene gas can be bubbled or otherwise dispersed through a reactor without substantially increasing the concentration of isobutylene dissolved in the liquid phase(s).

[0039] Without being bound to any particular theory, isobutylene and glycerol can react primarily when both are present in a liquid phase. By controlling the amount of isobutylene dissolved in a liquid phase with glycerol and/or mono-GTBEs and di-GTBEs, the rate of etherification can be controlled. By controlling the amount of isobutylene dissolved in a liquid phase, the rate of side reactions of isobutylene (e.g., oligomerization) can also be controlled. By way of non-limiting example, the etherification reaction of glycerol and isobutylene can be performed with a molar ratio of glycerol to isobutylene within the liquid phase of about 1 : 1 to about 20: 1.

[0040] In certain embodiments, isobutylene can be fed into one or more reactors in a liquid phase and can be converted to a gaseous phase in the reactor. Upon entering a reaction vessel within the reactor, the isobutylene liquid can be converted rapidly to isobutylene gas. In this rapid phase conversion, the isobutylene will "flash" and form rapidly expanding bubbles, which can improve mixing within the reactor. As isobutylene liquid is converted to isobutylene gas, the heat of evaporation of isobutylene can absorb heat from the reaction mixture. The absorption of heat can be beneficial, as the etherification reaction is exothermic overall. Accordingly, feeding isobutylene into a reactor in a liquid phase can help to control temperature within the reactor. Control of temperature can improve product selectivity and reaction reproducibility and decrease side product formation. [0041] Alternatively, isobutylene can be fed into one or more reactors in a gaseous phase.

[0042] Isobutylene in a gaseous phase can bubble or otherwise disperse through a liquid phase(s) in a reactor. The flow of gaseous isobutylene can aid in the mixing of liquid and gaseous phases within the reactor. Vapor bubbles of isobutylene can induce macroscopic convection patterns, which can improve mixing and mass transfer. Vapor bubbles of other gaseous substances present, which can include n-butane, isobutane, and/or n-butenes in certain embodiments, can also induce macroscopic convection patterns and improve mixing and mass transfer.

[0043] The reactors of the presently disclosed subject matter can be coupled to an overhead system for receiving gaseous isobutylene from the reactor. That is, isobutylene gas that does not react in an etherification reaction and does not remain dissolved in a liquid phase can be received and captured by the overhead system. The overhead system can recycle isobutylene back into the reactor. In certain embodiments, the overhead system can make up the recycled isobutylene with fresh isobutylene before feeding isobutylene back into the reactor. In certain embodiments the overhead system can collect isobutylene in a gaseous phase and then compress the isobutylene into a liquid phase or a gas/liquid mixture before recycling it.

[0044] The one or more liquid phases in the reactors of the presently disclosed subject matter can be removed from the reactor(s). When a liquid phase is removed from a reactor, the liquid phase can optionally be fed into a catalyst decanter, which can separate catalyst from the liquid phase. The liquid phase can be fed into an extraction column, which can separate glycerol, mono-GTBEs, di-GTBEs, and tri-GTBEs from the liquid phase.

Unconverted glycerol can be recycled and fed back into a reactor for further etherification reactions, while mono-, di-, and/or tri-GTBEs can be collected as reaction products.

Depending on the process and system, in certain embodiments some or all mono-GTBEs can be recycled into a reactor as a solvent and reactant for further etherification reactions rather than collected as reaction products.

[0045] Certain embodiments of the presently disclosed processes and systems for generating glycerol tert-butyl ethers include more than one reactor. For example, the presently disclosed processes and systems can include two, three, four, or more reactors in series. Each reactor can include an acid catalyst. Each reactor can be configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase. Glycerol and isobutylene can be fed into the first reactor, where they undergo an etherification reaction. A liquid reaction mixture, which includes GTBEs and unreacted glycerol, as well as a quantity of dissolved isobutylene, can be removed from the first reactor and fed into a second reactor. Unreacted isobutylene gas can be removed from the first reactor.

[0046] The isobutylene gas can be removed via an overhead system. The overhead system can recycle the isobutylene gas and recycle it into the first reactor. The overhead system can also feed isobutylene gas into the second reactor. A liquid reaction mixture can be passed from a first reactor to a second reactor, and from a second reactor to a third reactor, and from a third reactor to a fourth, and so on. Isobutylene gas can be removed from each reactor in the series and recycled. As the liquid reaction mixture passes from the first reactor through the second reactor and through any further reactors in the series, the concentration of GTBEs in the liquid reaction mixture will increase and the concentration of glycerol will decrease as the reaction progresses. The concentration of di-GTBEs and tri-GTBE, in particular, can increase as the liquid reaction mixture passes from the first reactor through the second reactor and through any further reactors in the series.

[0047] In the embodiments of the present disclosure where more than one reactor is used, the multiple reactors can be configured at different temperatures and pressures. By configuring different reactors at different temperatures and pressures, the concentrations of isobutylene dissolved in the liquid phase(s) within each reactor can be controlled and differentiated. In certain embodiments, the concentration of isobutylene in the first reactor can be lower than the concentration of isobutylene in the second reactor. By way of non- limiting example, this can be achieved by configuring the first reactor at a lower pressure and a higher temperature than the second reactor. In certain embodiments that further include a third reactor, the concentration of isobutylene in the second reactor can be lower than the concentration of isobutylene in the third reactor. By way of non-limiting example, this can be achieved by configuring the second reactor at a lower pressure and a higher temperature than the third reactor. In this way, a gradient of incrementally increasing isobutylene concentration can be created within the series.

[0048] A gradient of isobutylene concentration across a series of reactors can be advantageous. As noted previously, the concentration of GTBEs within a liquid reaction mixture will increase from the first reactor in a series to the second, and from the second to the third, and so on. As the concentration of GTBEs increases, and in particular as the concentration of di-GTBEs and tri-GTBE increases, the concentration of mono-GTBEs and glycerol can decrease proportionately. As the concentrations of mono-GTBEs and glycerol decrease, the overall reaction rate, as measured by consumption of isobutylene by etherification, can decline. It can therefore be helpful to boost reaction rate and drive conversion of glycerol and mono-GTBEs by increasing the concentration of isobutylene in the liquid phase(s) in the second and further reactors. Keeping the concentration of isobutylene in the liquid phase(s) in the first reactor relatively low can help suppress oligomerization of isobutylene in the first reactor

[0049] The multiple reactors can include different catalysts. In certain embodiments, the first reactor in a series of reactors can include an inexpensive catalyst, while the second and further reactors can include more expensive catalysts.

[0050] For the purpose of illustration and not limitation, FIG. 1 is a schematic representation of an exemplary system for generating glycerol tert-butyl ethers according to one embodiment of the disclosed subject matter. The system 100 of FIG. 1 includes a first reactor 101. The first reactor 101 is coupled to an isobutylene feed 102 and a glycerol feed 103. The system 100 further includes an overhead system 104 for receiving gaseous isobutylene from the first reactor 101. The overhead system 104 is coupled to the first reactor 101. The system 100 further includes a second reactor 105. The second reactor 105 is coupled to the first reactor 101 via line 106 and configured to receive a liquid feed from the first reactor 101. The second reactor 105 is further coupled to the overhead system 104 and configured to receive an isobutylene feed 107 from the overhead system 104.

[0051] The exemplary system 100 of FIG. 1 further includes a third reactor 108. The third reactor 108 is coupled to the second reactor 105 via line 109 and configured to receive a liquid feed from the second reactor 105. The third reactor 108 is further coupled to the overhead system 104 and configured to receive an isobutylene feed 110 from the overhead system 104.

[0052] The reactors 101, 105, 108 can include spargers adapted to introduce isobutylene gas into the reaction chambers of the reactors 101, 105, 108. The spargers can be connected to the isobutylene feeds 102, 107, 110.

[0053] The system 100 can include an isobutylene source 111. The isobutylene source 111 can be coupled to the isobutylene feeds 102, 107, 110. The isobutylene source 111 can be a mixed C4 stream. The system 100 can further include a glycerol source 112. The glycerol source 112 can be coupled to a glycerol flow 126. The glycerol flow 126 can direct glycerol into an extraction column 123. The extraction column 123 can be coupled to a glycerol and mono-GTBE flow 127, which can ultimately be coupled to the glycerol feed 103. [0054] The overhead system 104 can remove isobutylene gas 113 from the first reactor 101, second reactor 105, and third reactor 108. The overhead system 104 can also remove other C4 hydrocarbon gases (e.g., n-butane, isobutane, and n-butenes) from the reactors 101, 105, 108. These other gases can be present in the isobutylene gas 113. The overhead system can be coupled to a C4 condenser 114. The C4 condenser 114 can be coupled to a chilled water cooler 115. The C4 condenser can condense C4 hydrocarbon gases, including isobutylene gas, and convert them to liquids. Liquid C4 hydrocarbons, including liquid isobutylene, can be pumped by a C4 pump 116 through a liquid C4 flow 117.

[0055] A portion of the liquid C4 flow 117 can be recycled into the isobutylene feeds 102, 107, 110. A portion of the liquid C4 flow 117 can be sent to a side solvent recovery column 121, and part of the C4 hydrocarbons can be purged through a C4 purge 122. In this way, inert C4 components (e.g., n-butane, isobutane, and n-butenes) can be purged to limit their buildup within the system 100. In certain embodiments, the portion of the liquid C4 flow 117 sent to C4 purge 122 can be up to about 25% per cycle, e.g., about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 12%, about 15%, about 18%, about 20%, about 22%, or about 25%.

[0056] The system 100 can include a catalyst decanter 118. The catalyst decanter 118 can be coupled to the third column 108. The catalyst decanter 118 can receive a product flow from the third column 108. The catalyst decanter 118 can separate a catalyst from the product flow. For example, particulate catalysts (e.g., particles of a heterogeneous solid catalyst) can be separated from a slurry of GTBE products, glycerol, solvent, and catalyst. The catalyst decanter 118 can direct separated catalyst through a catalyst flow 119, which can return catalyst to the first reactor 101. The catalyst decanter 118 can be further coupled to a main solvent recovery column 120. The main solvent recovery column 120 can separate a solvent (e.g., TI-IF) from GTBEs and glycerol. The main solvent recovery column 120 can direct solvent through a solvent flow 125, which can recycle solvent into the first reactor 101. The main solvent recovery column 120 can direct glycerol and GTBE products through a glycerol and GTBEs flow 129. The glycerol and GTBEs flow 129 can direct glycerol and GTBEs to an extraction column 123.

[0057] The extraction column 123 can separate glycerol, mono-GIBEs, di-GTBEs, and tri- GTBE. Di-GTBEs and tri-GTBEs can be directed through an outlet line 124 and collected as products, while glycerol and mono-GTBEs can be directed through a glycerol and mono-GTBEs flow 127. The glycerol and mono-GTBEs flow 127 can be joined with the catalyst flow 119 to create a combined glycerol, mono-GTBEs, and catalyst flow 128. The combined glycerol, mono-GTBEs, and catalyst flow 128 can be coupled to the glycerol 103 feed and feed glycerol, mono-GTBEs, and catalyst into the first reactor 101. In this way, glycerol, mono-GTBEs, and catalyst can be recycled into the first reactor 101 for further reaction.

[0058] The second reactor 105 can be coupled 106 to the first reactor 101 and the third reactor 108 can be coupled 109 to the second reactor 105 through liquid-liquid connections. The three reactors 101, 105, 108 can be connected in series or they can be parallel. The reactors 101, 105, 108 can be slurry bubble column reactors. The reactors 101, 105, 108 can be operated at individually configured temperatures of 60°C to 90°C and at individually configured pressures of 3 bar to 15 bar (300 kPa to 1500 kPa).

[0059] The temperature of the first reactor 101 can be higher than the temperature of the second reactor 105, which can be higher than the temperature of the third reactor 108. The pressure of the first reactor 101 can be lower than the pressure of the second reactor 105, which can be lower than the temperature of the third reactor 108. In this way, the system can create an overall gradient of isobutylene concentration within the liquid phases of the first reactor 101 the second reactor 105, and the third reactor 108. The concentration of isobutylene within the liquid phases of the first reactor 101 the second reactor 105, and the third reactor 108 can increase incrementally from the first reactor 101 to the second reactor 105 to the third reactor 108.

[0060] The residence time of the liquid phases within the first reactor 101, the second reactor 105, and the third reactor 108 can be independently optimized by adjustment of the flow rates through each reactor. The residence times for the liquid phases within each reactor 101, 105, 108 can be of about 3 to 5 minutes to about 3 to 5 hours.

[0061] Advantages of the presently disclosed processes and systems for generating glycerol tert-butyl ethers can include improved product quality, reduced levels of side products and impurities, and improved economy and efficiency. The processes and systems of the present disclosure enable generation of glycerol tert-butyl ethers in a controlled fashion. The residence time distribution within the reactor or multiple reactors can be carefully tuned and optimized by adjusting temperature, pressure, flow rate, and other variables. The processes and systems of the present disclosure can enable plug flow-like residence time distributions for glycerol and GTBEs. The concentrations of glycerol and isobutylene can be controlled independently, as noted above. One catalyst can be used, or multiple catalysts can be used in concert. All of these factors can work together to create improved processes and systems for generating a glycerol tert-butyl ether. [0062] The processes and systems disclosed herein include at least the following embodiments:

[0063] Embodiment 1 : A process for generating a glycerol tert-butyl ether, comprising: feeding glycerol and isobutylene into a reactor; and reacting glycerol with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction, wherein: the reactor comprises an acid catalyst; and the reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase.

[0064] Embodiment 2: The process of Embodiment 1, wherein a solvent is fed into the reactor with glycerol and isobutylene.

[0065] Embodiment 3: The process of Embodiment 2, wherein the solvent is tetrahydrofuran, mono-tert-butyl glycerol ether, or a combination comprising at least one of the foregoing.

[0066] Embodiment 4. The process of any of Embodiments 1-3, wherein isobutylene is fed into the reactor as part of a mixed C4 stream.

[0067] Embodiment 5. The process of any of Embodiments 1-4, wherein isobutylene is fed into the reactor in a liquid phase and is converted to a gaseous phase in the reactor.

[0068] Embodiment 6. A process for generating a glycerol tert-butyl ether, comprising: feeding glycerol and isobutylene into a first reactor; reacting glycerol with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction, wherein: the first reactor comprises an acid catalyst; and the first reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase; removing a liquid reaction mixture from the first reactor; feeding the liquid reaction mixture into a second reactor; and reacting glycerol in the liquid reaction mixture with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction, wherein: the second reactor comprises an acid catalyst; and the second reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase.

[0069] Embodiment 7. The process of Embodiment 6, wherein the first reactor and the second reactor are configured at different temperatures and pressures.

[0070] Embodiment 8. The process of Embodiment 6 or Embodiment 7, wherein the concentration of isobutylene in the first reactor is lower than the concentration of isobutylene in the second reactor.

[0071] Embodiment 9. The process of Embodiment 6 or Embodiment 7, further comprising: removing a second liquid reaction mixture from the second reactor; feeding the second liquid reaction mixture into a third reactor; and reacting glycerol in the second liquid reaction mixture with isobutylene to obtain a glycerol tert-butyl ether through an

etherification reaction, wherein: the third reactor comprises an acid catalyst; and the third reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase.

[0072] Embodiment 10. The process of Embodiment 9, wherein the temperature and pressure of the first reactor, the second reactor, and the third reactor are each configured at different temperatures and pressures.

[0073] Embodiment 11. The process of Embodiment 10, wherein the concentration of isobutylene in the first reactor is lower than the concentration of isobutylene in the second reactor and the concentration of isobutylene in the second reactor is lower than the concentration of isobutylene in the third reactor.

[0074] Embodiment 12. The process of any of Embodiments 6-11, wherein the first reactor comprises an acid catalyst different from the acid catalyst of the second reactor.

[0075] Embodiment 13. The process of any of Embodiments 6-12, wherein a solvent is fed into the first reactor with glycerol.

[0076] Embodiment 14. The process of Embodiment 13, wherein the solvent is tetrahydrofuran, mono-tert-butyl glycerol ether, or a combination comprising at least one of the foregoing.

[0077] Embodiment 15. The process of any of Embodiments 6-14, wherein isobutylene is fed into the reactor as part of a mixed C4 stream.

[0078] Embodiment 16. The process of any of Embodiments 6-15, wherein isobutylene is fed into the reactor in a liquid phase and is converted to a gaseous phase in the reactor.

[0079] Embodiment 17. A system for generating a glycerol tert-butyl ether using an acid catalyst, comprising: a reactor configured to receive the acid catalyst; an isobutylene teed coupled to the reactor for supplying isobutylene thereto; and a glycerol feed coupled to the reactor for supplying glycerol thereto, wherein: the reactor is adapted to operate at a temperature and a pressure at which the isobutylene is in a gaseous phase and the glycerol is in a liquid phase.

[0080] Embodiment 18. A system for generating a glycerol tert-butyl ether using acid catalysts, comprising: a first reactor configured to receive a first acid catalyst, an isobutylene feed coupled to the first reactor for supplying isobutylene thereto; a glycerol feed coupled to the first reactor for supplying glycerol thereto; an overhead system coupled to the tlrst reactor for receiving gaseous isobutylene from the first reactor; and a second reactor configured to receive a second acid catalyst coupled to the overhead system for receiving an isobutylene feed from the overhead system and further coupled to the first reactor for receiving a liquid feed from the first reactor.

[0081] Embodiment 19. The system of Embodiment 18, wherein the first reactor is adapted to operate at a first temperature and a first pressure and the second reactor is adapted to operate at a second temperature and a second pressure.

[0082] Embodiment 20. The system of Embodiment 19, wherein the first temperature and the first pressure are different from the second temperature and the second pressure.

[0083] Embodiment 21. The system of any of Embodiments 18-21, wherein the first acid catalyst is different from the second acid catalyst.

[0084] In general, the invention may alternately comprise, consist of, or consist essentially of, any appropriate components herein disclosed. The invention may additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any components, materials, ingredients, adjuvants or species used in the prior art compositions or that are otherwise not necessary to the achievement of the function and/or objectives of the present invention. The endpoints of all ranges directed to the same component or property are inclusive and independently combinable (e.g., ranges of "less than or equal to 25 wt , or 5 wt% to 20 wt ," is inclusive of the endpoints and all intermediate values of the ranges of "5 wt% to 25 wt ," etc.). Disclosure of a narrower range or more specific group in addition to a broader range is not a disclaimer of the broader range or larger group. "Combination" is inclusive of blends, mixtures, alloys, reaction products, and the like. Furthermore, the terms "first," "second," and the like, herein do not denote any order, quantity, or importance, but rather are used to denote one element from another. The terms "a" and "an" and "the" herein do not denote a limitation of quantity, and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. "Or" means "and/or." The suffix "(s)" as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term (e.g., the film(s) includes one or more films). Reference throughout the specification to "one embodiment", "another embodiment", "an embodiment", and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments. [0085] The modifier "about" used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity). The notation "+ 10%" means that the indicated measurement can be from an amount that is minus 10% to an amount that is plus 10% of the stated value. The terms "front", "back", "bottom", and/or "top" are used herein, unless otherwise noted, merely for convenience of description, and are not limited to any one position or spatial orientation. "Optional" or "optionally" means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event occurs and instances where it does not. Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. A "combination" is inclusive of blends, mixtures, alloys, reaction products, and the like.

[0086] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference

[0087] While particular embodiments have been described, alternatives,

modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.

[0088] I/we claim:

Claims

CLAIMS:

1. A process for generating a glycerol tert-butyl ether, comprising:

feeding glycerol and isobutylene into a reactor; and

reacting glycerol with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction, wherein:

the reactor comprises an acid catalyst; and

the reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase.

2. The process of Claim 1 , wherein a solvent is fed into the reactor with glycerol and isobutylene.

3. The process of Claim 2, wherein the solvent is tetrahydrofuran, mono-tert-butyl glycerol ether, or a combination comprising at least one of the foregoing.

4. The process of any of Claims 1-3, wherein isobutylene is fed into the reactor as part of a mixed C4 stream.

5. The process of any of Claims 1-4, wherein isobutylene is fed into the reactor in a liquid phase and is converted to a gaseous phase in the reactor.

6. A process for generating a glycerol tert-butyl ether, comprising:

feeding glycerol and isobutylene into a first reactor;

the first reactor comprises an acid catalyst; and

the first reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase;

removing a liquid reaction mixture from the first reactor;

feeding the liquid reaction mixture into a second reactor; and

reacting glycerol in the liquid reaction mixture with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction, wherein:

the second reactor comprises an acid catalyst; and the second reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase.

7. The process of Claim 6, wherein the first reactor and the second reactor are configured at different temperatures and pressures.

8. The process of Claim 6 or Claim 7, wherein the concentration of isobutylene in the first reactor is lower than the concentration of isobutylene in the second reactor.

9. The process of Claim 6 or Claim 7, further comprising:

removing a second liquid reaction mixture from the second reactor;

feeding the second liquid reaction mixture into a third reactor; and

reacting glycerol in the second liquid reaction mixture with isobutylene to obtain a glycerol tert-butyl ether through an etherification reaction, wherein:

the third reactor comprises an acid catalyst; and

the third reactor is configured at a temperature and a pressure at which isobutylene is in a gaseous phase and glycerol is in a liquid phase.

10. The process of Claim 9, wherein the temperature and pressure of the first reactor, the second reactor, and the third reactor are each configured at different temperatures and pressures.

11. The process of Claim 10, wherein the concentration of isobutylene in the first reactor is lower than the concentration of isobutylene in the second reactor and the concentration of isobutylene in the second reactor is lower than the concentration of isobutylene in the third reactor.

12. The process of any of Claims 6-11, wherein the first reactor comprises an acid catalyst different from the acid catalyst of the second reactor.

13. The process of any of Claims 6-12, wherein a solvent is fed into the first reactor with glycerol.

14. The process of Claim 13, wherein the solvent is tetrahydrofuran, mono-tert- butyl glycerol ether, or a combination comprising at least one of the foregoing.

15. The process of any of Claims 6-14, wherein isobutylene is fed into the reactor as part of a mixed C4 stream.

16. The process of any of Claims 6-15, wherein isobutylene is fed into the reactor in a liquid phase and is converted to a gaseous phase in the reactor.

17. A system for generating a glycerol tert-butyl ether using an acid catalyst, comprising:

a reactor configured to receive the acid catalyst;

an isobutylene teed coupled to the reactor for supplying isobutylene thereto; and a glycerol feed coupled to the reactor for supplying glycerol thereto, wherein: the reactor is adapted to operate at a temperature and a pressure at which the isobutylene is in a gaseous phase and the glycerol is in a liquid phase.

18. A system for generating a glycerol tert-butyl ether using acid catalysts, comprising:

a first reactor configured to receive a first acid catalyst,

an isobutylene feed coupled to the first reactor for supplying isobutylene thereto; a glycerol feed coupled to the first reactor for supplying glycerol thereto;

an overhead system coupled to the tlrst reactor for receiving gaseous isobutylene from the first reactor; and

a second reactor configured to receive a second acid catalyst coupled to the overhead system for receiving an isobutylene feed from the overhead system and further coupled to the first reactor for receiving a liquid feed from the first reactor.

19. The system of Claim 18, wherein the first reactor is adapted to operate at a first temperature and a first pressure and the second reactor is adapted to operate at a second temperature and a second pressure.

20. The system of Claim 19, wherein the first temperature and the first pressure are different from the second temperature and the second pressure.

21. The system of any of Claims 18-21, wherein the first acid catalyst is different from the second acid catalyst.