Gases catalysis

Wakabayashi, F. and Domen, K. (1997) A new method for characterizing solid surface acidity - an infrared spectroscopic method using probe molecules such as N2 and rare gases. Catalysis Surveys from Japan 1 181. 

Barbier, Jr., J., and Duprez, D. 1993. Reactivity of steam in exhaust gas catalysis. I. Steam and oxygen/steam conversions of carbon monoxide and of propane over PtRh catalysts. Appl. Catal. B Environ. 3 61-83. 

Consequently, degradation of halogenated compounds in gaseous effluents, especially in diluted effluents, is often problematic, dehalogenation being the limiting step. In order to overcome this problem, a new process, based on solid/gas catalysis with whole dehydrated cells as the catalyst, has been proposed [14]. The aim is to convert halogenated compounds into alcohols. 

Solid/gas catalysis could also be a tool to overcome the limiting step of deha-logenation. Nevertheless, working with whole dehydrated cells as catalyst requires the control of several operational parameters. 

Dehydrogenases also represent a class of interesting enzymes since enantiose-lective reduction of ketones can lead to the production of enantiomerically pure secondary alcohols for the fine chemicals industry. Compared to liquid systems, in which the cofactor is often eliminated by the circulating phase in continuous systems, solid/gas catalysis can be highly suitable since it has been demonstrated that the cofactor is stable and its regeneration effective by addition of a second substrate. Also, stereoselective oxidation of secondary alcohols by these systems can help in the resolution of racemic mixtures. 

Solid/gas catalysis appears today as probably the most appropriate experimental tool for validating molecular modeling experiments, and this should help to answer the following questions ... 

The gas stream containing sulfur dioxide is either dried before passing to the catalytic oxidation step, or is oxidized in the presence of water vapor with subsequent acid condensation and removal. When acid is produced from elemental sulfur, the air used for sulfur burning is predried. In all cases, typical plant designs use sulfuric acid from the process as a drying agent. Wet catalytic oxidation is relatively uncommon. Some applications of Haldor Topsme s WSA-2 wet gas catalysis process are described in the literature (97). 

Rostrup-Nielsen, J.R., 1993, Production of synthesis gas, Catalysis Today, 18, p305-324. 

A variant of the contact process is operated in coking plants, the moist gas catalysis process, in which wet sulfur dioxide from the combustion of hydrogen sulfide is converted into sulfuric acid. In this process hydrogen sulfide, from coking plants, is converted to sulfur dioxide and water with an excess of air ... 

Echigo, M., Shinke, N., Takami, S., Higashiguchi, S., Hirai, K., and Tabata, T. Development of residential PEFC cogeneration systems Ru catalyst for CO preferential oxidation in reformed gas. Catalysis Today, 2003, 84, 209. 

Stainless steel N2O, 26° /3 90Sr-90Y 3 X 1020 ev/gm, hr to gas Catalysis presumed from abnormal yields and lack of pressure effect Metal present as walls of container (219a)... 

We have studied the O-alkylation of catechol in guaiacol by solid-gas catalysis. In this reaction, 1,2-dimethoxybenzene 2 (veratrole) can be produced as a coproduct and also some C-alkylated derivatives as by-products. We have chosen to mainly study phosphates derivatives and to realize a large screening of catalysts. 

M. Nonnenmann, Metal Supports for Exhaust Gas Catalysis , SAE Paper 850131, February 1985. 

REACTIVITY OF STEAM IN EXHAUST GAS CATALYSIS. PART II SINTERING AND REGENERATION OF Rh AND PtRh CATALYSTS IN PROPANE OXIDATION... 

The surface of ceria being readily reduced at low temperature (< 473K) in the presence of noble metals [1,4], step 3 is expected to be very rapid under the usual conditions of exliaust gas catalysis (T=673-773K). 

It is seen from the table that some healing of surface defects is possible without undue reduction of particle size. In general, however, the temperature of any heat treatment of active materials must be strictly controlled to avoid deleterious effects. In heterogeneous gas catalysis, reaction temperatures exceeding those recommended in the table are often unavoidable this leads to a... 

Torres, W., Pansare, S.S. and GoodwinJr, J.G. (2007) Hot gas removal of tars, ammonia, and hydrogen sulfide from biomass gasification gas. Catalysis Reviews, 49, 407 56. 

Grunes J, Zhu J, Somoijai GA. Catalysis and nanoscience. In Nanotechnology in catalysis, Vol 1. Zhou B, Hermans S, Somoijai G, editors. London Springer, 2004 1-15. 

The GB-catalyzed term kg,[GB][HNu][Sub] is also kineticaUy indistinguishable from SB-GA-catalyzed term ksi,8 [HO][HNu][Sub][GBH+]. The occurrence of such a term in the rate law predicts the possible occurrence of GB-GA catalyzed term kjb [GB][HNu][Sub][GBH+], if the effect of the basicity difference of HO and GB is nearly counterbalanced by the effect of their concentration difference. Thus, the absence of GB-GA catalysis may qualitatively rule out the presence of SB-GA catalysis. 

The realization of the occurrence of intermolecular GA catalysis comes from the experimental fact of the presence of a kinetic term kgJBH+][NuH][Sub] (where BH+ is the GA, NuH is the nucleophile, and Sub is the substrate) in the rate law for the nucleophilic reaction between NuH and Sub in the presence of BH+. But this kinetic term is kinetically indistinguishable from kinetic term k[H+][B][NuH][Sub], which represents SA-GB catalysis or SA-nucleophilic catalysis. However, these kinetically indistinguishable catalytic mechanisms can be resolved, at least qualitatively, as described in the following text. 

---