Gulf process

Cherts CHESS Chevrefeuille Chevrel phase Chevron-Gulf process Chevron process... 

Emert Also known as the Gulf process, the University of Arkansas process, and SSF. A process for converting cellulose to ethanol by simultaneous saccharification and fermentation. Invented by G. H. Emert. 

The Chevron/Gulf process also uses triethylaluminum but in a catalytic reaction at higher temperature. Reaction conditions exert a strong effect on product distribution. Under the proper conditions (200-250°C, 140-270 atm) the rates of insertion and chain transfer (displacement) are comparable, ensuring frequent p-hydrogen elimination. A broader product distribution compared with that of the two-step ethyl process is obtained. 

Chevron-Gulf process -ethylene oligomerization [OLEFINS, HIGFIER] (Vol 17)... 

Direet eonversion of eyelohexane to adipie aeid by air is made possible by the use of a high eoneentration of eobalt aeetate as catalyst (Gulf process). Adipic acid is obtained with 70-75% selectivity at 80-85% conversion of cyclohexane. The main by-product is glutaric acid. It is believed that at these high concentrations, cobalt is not only a catalyst for hydroperoxide decomposition, but directly reacts with cyclohexane (Equation Bl). 

In this stoichiometric reaction sequence, a Poisson distribution of a-oletin products is obtained. The main disadvantage of this process is the large amount of aluminium alkyls needed in an industrial plant. To overcome this drawback, improvements of the process were developed by several companies. Only the two most important examples, the Gulf process and the Ethyl process, will be described in more detail. Shell developed a different route based on a nickel complex catalyst. Though other processes based on different transition metal catalysts have been developed, only the three processes mentioned above became important [16]. 

Many companies have studied the optimization of catalyst composition and process conditions in order to improve the performance of the reaction and the economics ofthe process. In the Gulf process, the reaction is carried out at 90-100 °C, with a Co(III) acetate catalyst and acetic acid as the solvent [17]. The molar selectivity is around 70-75%, for a cyclohexane conversion that can be as high as 80-85%. The high concentration of Co(III) acetate used also favors the direct reaction ofthe cation with cyclohexane, generating the cydohexyl radical. In fact, in Gulf patents the reaction is reported to occur in a critical amount of Co(III) (25-150 mmoles per mole of cyclohexane). The catalyst is activated during the initial induction period, and water is also added in the initial stage to enhance the selectivity to AA, but the rate of production decreases because the induction period increases. 

The second step in the direct ethanol process is that of enzyme production. The Gulf process utilizes a mutant strain of Trichoderma reesei, grown continuously to produce a complete cellulase system. The residence time is 48 hours. Enzyme production begins on a spore plate with subsequent scale-up to the enzyme production vessel size to be used. Our pilot plant facility has 300-gal enzyme reactors. 

Prior to introduction of the SHOP process a-olefins were produced by pyrolysis of waxes above 500 °C (e.g.. Chevron process) or by olefin oligomerization with triethylalmninium (Gulf process). However, both produce olefins that are less suited to market requirements [17]. 

In the Gulf process (Figure 19.16), ground coal which has been slurried with a recycle solvent is introduced with hydrogen into a catalytic, fixed-bed reactor at 480°C (900°F) and 2000 psi. The products are flashed to remove gases from the liquids which are then separated into a synthetic crude oil, recycle solvent, and solids. The solids are coked to yield more liquids. 

Chemical Co. [283-287], Ethyl Corp. [288], and by Shell Oil Co. [288-291]. The Gulf and Ethyl processes use EtsAl as catalyst although they differ in some details. In the Ethyl process, in contrast to the Gulf process, the products are recycled to increase the amount of the most desirable linear a-olefins C6-Ci4. This leads, unfortunately, to higher branched olefin content in the yield as a result of higher a-olefins reactions with alkylaluminum compounds. 

The Ethyl process [292] is carried out at 100°C under 210 psig pressure, and the Gulf process at 190 C under 4000 psig uses 14% EtsAl in heptane solution as catalyst. The ethylene conversion reaches 85%. 

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