Catalytic re-forming process

The catalytic re-forming process is a major source of hydrogen gas, which is also a potential fuel. 

Catalytic re-forming process Process that increases octane rating of straight-run gasoline by converting straight-chain hydrocarbons to branched-chain hydrocarbons and aromatics... 

The feedstock dependency is based on specially prepared NBR (discussed in the earlier nitrile rubber section), but sometimes with a proprietary third monomer and hydrogen gas. The hydrogen is usually obtained as a byproduct of petroleum cracking and catalytic re-forming processes shown in Figure 4.17. 

Petroleum products undergo catalytic hydrodesulfurization and re-forming processes. Catalysts in automobile exhaust systems convert pollutants (hydrocarbons, CO, NO) to... 

Barbieri, G. and F. P. Di Maio Simulation of the methane steam re-forming process in a catalytic Pd-membrane reactor , 7m4. Eng. Chem. 36,2121-2127 (1997). Basile, A., L. Paturzo and F. Lagana The partial oxidation of methane to syngas in a palladium membrane reactor simulation and experimental studies , Catal. Today, 61,65-75 (2001). 

STAR [Steam Active Re-forming] A catalytic reforming process for converting aliphatic hydrocarbons to olefins or aromatic hydrocarbons. Hydrocarbons containing five or fewer carbon atoms are converted to olefins. Those containing six or more are dehydrocy-clized to aromatic hydrocarbons. The reactions take place in the vapor phase, in a fixed catalyst bed containing a noble metal catalyst, in the presence of steam. Demonstrated on a semi-commercial scale and offered for license by Phillips Petroleum Company. The first commercial plant was built for Coastal Chemicals in Cheyenne, WY, in 1992 another for Polibutenos Argentinos in 1996. 

From 1943 to 1948 he was consultant to Hydrocarbon Research, Inc., and from 1948 until his death a consultant to the Socony-Vacuum laboratories in connection with the synthesis of gasoline and the cracking and re-forming of petroleum by catalytic processes. 

The cobalt center in MeCbl, one of the two important B12 coenzymes, is clearly involved in key steps in catalytic methyl transfer processes. Here, the Co center cycles between Co(I) and Co(III)CH3. In methionine synthase, the proposed mechanism involves direct nucleophilic attack on the C of the Co(III)CH3 group. In model reactions, the thiolate most frequently simply binds tram to the alkyl group to give a product recently established by an x-ray study of a model system. The protein may block access to the Co, thus preventing this reaction common in models. It is likely that the reactive form of the bound cofactor is five-coordinate in the key point in the catalytic cycle. This reactive form will lead to a four-coordinate Co(I) species. The axial coordination of the cofactor by a protein imidazole allows for a finer tuning of the Cbl chemistry and may permit control of the coordination number. Thus, recoordination of Co in the Co(I) state may facilitate attack on methyltetrahydrofolate and re-formation of Co(III)CH3. 

Michael reactions of silyl enolates or ketene silyl acetals with a, -unsaturated carbonyl compounds are among the most important carbon-carbon bond-forming processes in organic synthesis. Sc(OTf)3 was found to be effective [4], and the reactions proceeded smoothly in the presence of a catalytic amount of Sc(OTf)3, under extremely mild conditions, to give the corresponding 1,5-dicarbonyl compounds in high yields after acid work-up (Eq. 2). Silyl enolates derived from ketones, thioesters, and esters were applicable, and no 1,2-addition products were obtained. The products could, furthermore, be isolated as synthetically valuable silyl enol ethers (I) when acid-free work-up was performed. The catalyst could be recovered almost quantitatively and could be re-used. 

Only the conversion of synthesis gas as described under 3 forms the subject of this review. The chemistry of the catalytic processes is, of course, independent of the way in which the synthesis gas was manufactured besides coal gasification the steam re-forming of natural gas is a well-known route to produce synthesis gas, although with a higher Hj/CO ratio. 

Two steady-state kinetic constants are most useful in evaluating biocatalytic reactions. "k J is often known as the turnover number and higher values indicate more catalytically efficient enzymes. This first-order rate constant describes the speed at which an enzyme converts bound substrates to products and re-forms the free enzyme to prepare for the next round of catalysis. It includes both the "chemical" steps (bond making and bond breaking) as well as the product release step(s). Note that it is not uncommon for product release to be the slowest step. As a practical matter, one normally seeks enzymes with > 1 s under the process conditions to ensure reasonable space-time yields along with acceptable catalyst loading levels. 

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