Hydrogen incentives

The present economic and environmental incentives for the development of a viable one-step process for MIBK production provide an excellent opportunity for the application of catalytic distillation (CD) technology. Here, the use of CD technology for the synthesis of MIBK from acetone is described and recent progress on this process development is reported. Specifically, the results of a study on the liquid phase kinetics of the liquid phase hydrogenation of mesityl oxide (MO) in acetone are presented. Our preliminary spectroscopic results suggest that MO exists as a diadsorbed species with both the carbonyl and olefin groups coordinated to the catalyst. An empirical kinetic model was developed which will be incorporated into our three-phase non-equilibrium rate-based model for the simulation of yield and selectivity for the one step synthesis of MIBK via CD. 

An informative set of calculations was carried out by Brandt et al, coupled to experimental studies that demonstrated first-order dependence of the turnover rate on both catalyst and H2, and zero-order dependence on alkene (a-methyl-(E)-stilbene) concentration [71]. The incentive for this investigation was the absence of any characterized advanced intermediates on the catalytic pathway. As a result of the computation, a catalytic cycle (for ethene) was proposed in which H2 addition to iridium was followed by alkene coordination and migratory insertion. The critical difference in this study was the proposal that a second molecule of H2 is involved that facilitates formation of the Ir alkylhydride intermediate. In addition, the reductive elimination of R-H and re-addition of H2 are concerted. This postulate was subsequently challenged. For hydrogenation of styrene by the standard Pfaltz catalyst, ES-MS analysis of the intermediates formed at different stages in the catalytic cycle revealed only Ir(I) and Ir(III) species, supporting a cycle (at least under low-pressure conditions in the gas... 

Since most transfer hydrogenation catalysts employ precious metals, a high number of turnovers are required in order to make their use economic. As the ligands are simply made they are generally of low cost. In our experience, for the average pharmaceutical intermediate, a substrate catalyst ratio (SCR) of about 1000 1 is sufficient for the catalysts contribution to the product cost to be minor. These SCRs are regularly achieved, and so from an economic standpoint there has been little incentive to recover and recycle the catalyst, unless a low-cost product is required. The recovery of precious metals from waste streams provides another way in which costs can be minimized. 

The enantioselective hydrogenation of C=N bonds is the least-developed hydrogenation reaction, even though many active ingredients contain chiral amine moieties. The main reason for this situation is that effective catalysts - mainly Ir-diphosphine complexes - have been developed only during the past 10 years [124]. A major incentive for the development of more active catalysts was the chiral switch of metolachlor made in 1997 by Ciba-Geigy [125, 126]. 

The problems facing the development of a hydrogen infrastructure include the lack of demand for cars and trucks with limited fueling options and any incentive to invest in a fueling infrastructure unless there are enough vehicles on the road. 

The above reaction can be carried out in the presence of a variety of catalysts including Ni, Cu/Zn, Cu/SiO, Pd/SiO, and Pd/ZnO. In the case of coal, it is first pulverized and cleaned, then fed to a gasifier bed where it is reacted with oxygen and steam to produce the syngas. A 2 1 mole ratio of hydrogen to carbon monoxide is fed to a fixed-catalyst bed reactor for methanol production. Also, the technology for making methanol from natural gas is already in place and in wide use. Ciurent natural gas feedstocks are so inexpensive that even with tax incentives renewable methanol has not been able to compete economically. 

Much of the research pursued by the authors of this paper and by their associates has involved studies of the catalytic hydrogenation of coals in the absence of solvent. The technique has been used to elucidate the mechanisms of catalytic coal liquefaction and to provide simultaneously some insight into the structure of coals. Peter Given was directly instrumental in providing the incentive for this research which has extended since 1983. Previous findings were disseminated through several publications (4-8. In this paper, some of the earlier data have been collated with more recent results (9) to provide an account of the relevance of these studies to the two-component concept. 

The hydrogen and fuel cells projects are funded by a mix of public and private sources and through tax incentives. The estimated annual budget is over 30 million, which includes about 8-10 million in public funding. 

Removal of H2S and acid gases from the hydrogenation reactor process stream and also from the raw gases obtained from gasification of the heavy residual is required. The incentive for H2S removal and recovery of elemental sulfur in this case is environmental. 

Another major chlorinated hydrocarbon is vinyl chloride. For many years acetylene was the sole raw material for the production of vinyl chloride by a catalytic fixed bed vapor-phase process. This process is characterized by high yields and modest capital investment. Nevertheless, the high relative cost of acetylene provided an incentive to replace it in whole or in part by ethylene. The first step in this direction was the concurrent use of both raw materials. Ethylene was chlorinated to di-chloroethane, and the hydrogen chloride derived from the subsequent dehydrochlorination reacted with acetylene to form additional vinyl chloride. 

One of the economic incentives for the study of reaction (44) is that the reaction relates to the successful development of methanol—oxygen and hydrogen—oxygen fuel cells which are capable of extremely efficient conversion of the energy contained in a fuel to electricity. 

---