Showing papers in "Catalysis Reviews-science and Engineering in 1986"
TL;DR: Partial oxidation is a widely used process to convert hydrocarbons and alcohols to valuable oxygen-containing chemicals as discussed by the authors, however, the direct utilization of these reactions for the manufacture of formaldehyde and methanol has remained extremely difficult.
Abstract: Partial oxidation is a widely used process to convert hydrocarbons and alcohols to valuable oxygen-containing chemicals. Although methane is the simplest hydrocarbon which gives formaldehyde and methanol as partial oxidation products, the direct utilization of these reactions for the manufacture of formaldehyde and methanol has remained extremely difficult. During the 1940s, two processes for the conversion of methane to formaldehyde were developed in Germany [l]. The first process used NO as a catalyst, and a commercial plant using this process was known to have been in operation in Copsa Mica in Romania. The second process used a combination of ozone and barium peroxide as the catalyst. In the current industrial practice, however, methane is converted to HCHO through a three-step process involving high temperature steam reforming, low pressure methanol synthesis, and oxidative dehydrogenation of methanol to formaldehyde, as shown by Unlike steam reforming, direct oxidation does not require ener...
410 citations
TL;DR: Weisz and V. J. Frilette as discussed by the authors described the catalytic properties of small pore molecular sieve zeolites, and great strides in the use of shape-selective zeolite have been made, both scientifically and technologically.
Abstract: In the 26 years since the term “shape-selective catalysis” was coined by P. B. Weisz and V. J. Frilette [1] to describe the unique catalytic properties of small pore molecular sieve zeolites, great strides in the use of shape-selective zeolites have been made, both scientifically and technologically. Since then, in addition to small pore zeolites, synthetic medium pore zeolites, such as ZSM-5 [2], ZSM-11 [3], ZSM-22 [4], ZSM-23 [5], ZSM-35 [6], ZSM-38 [7], ZSM-48 [8], etc., have been discovered. The availability of these synthetic medium pore zeolites has expanded the realm of “shape selectivity” beyond the original discovery of selective conversion of straight chain molecules to include certain branched molecules, single-ring aromatics, naphthenes, and nonhydrocarbons with a critical molecular dimension smaller than about 6 A.
223 citations
TL;DR: In this paper, the authors present a theoretical explanation for carbon monoxide on platinum catalytic catalytic reactions, which poses difficulties and challenges to both the experimentalist and the theoretician, due to the frequent observations of hysteresis, associated with steady-state multiplicity, and self-sustained oscillations in the reaction.
Abstract: Although the oxidation of carbon monoxide on platinum is one of the oldest known catalytic reactions and one of the most thoroughly studied, it continues to pose difficulties and challenges to both the experimentalist and the theoretician. For the most part, these are due to the frequent observations of hysteresis, associated with steady-state multiplicity, and self-sustained oscillations in the reaction and to the fact that no generally accepted theoretical explanation for them is at hand. even though a large number of studies have addressed the subject.
202 citations
TL;DR: In this paper, the role of the rutile structure of antimony-based catalysts in allylic oxidation reactions has been examined, showing that antimony oxides stabilize in matrices with rutiles.
Abstract: Several authors have correlated catalyst structure to catalytic behavior in selective oxidation reactions. Sleight [1] reviewed the importance of the scheelite structure for the allylic oxidation and ammonoxidation of olefins; Grasselli and co-workers [2–4] extensively examined the relationship between structure and catalytic activity of bismuth-molybdates, uranium-antirnonates, and bismuth-cerium molybdates. Bordes and Courtine [5] correlated the activity in mild oxidation of 1-butene to the properties of the structure of vanadium-phosphorus oxides. However, little attention has been given in the literature to the role of the rutile structure in allylic oxidation reactions even though the high activity and selectivity of antimony oxides stabilized in matrices with rutile structure (SnO2 and FeSbO4) in olefins oxidation and ammonoxidation have been known for several years. Furthermore, Tables 1 and 2 indicate that the kinetic and catalytic behavior of antimony-based catalysts in allylic oxidation...
82 citations
TL;DR: In this paper, the authors proposed a model of the active sites of a heterogeneously catalyzed reaction and found that the most active sites occur at a few distinct places on the catalyst's surface.
Abstract: In 1925, H. S. Taylor [1] hypothesized that a heterogeneously catalyzed reaction occurs predominantly at a few distinct places on the catalyst's surface called “active sites.” Many models of the active site have been proposed [1–32] over the years. However, at present there is little agreement about what causes the active sites to have special catalytic properties.
77 citations
TL;DR: The importance of zeolites as catalysts hardly needs to be emphasized as discussed by the authors, and the exponential increase in research activity over the last 10 years is evidence of worldwide recognition of the potential of the zeolite catalysts.
Abstract: The importance of zeolites as catalysts hardly needs to be emphasized. In the recent past the research activity in this area registered a noticeable increase after the discovery of ZSM-type zeolites. A single-step conversion of methanol into a mixture of hydrocarbons, predominantly in the gasoline range, would have been considered highly improbable before this discovery. Apart from their unusual shape selectivity, the low coking character of these zeolites is of particular importance to industrial practice. The discovery has clearly demonstrated promise for further research on the synthesis of new types of zeolites and exploration of novel reactions on zeolite catalysts. The exponential increase in research activity [68, 220] observed over the last 10 years is evidence of worldwide recognition of the potential of zeolite catalysts.
50 citations
TL;DR: In this article, the most sensitive probe of catalysts performance will continue to be the rate and selectivity of a chemical reaction, however, these macroscopic observations, adequate for determining how good a catalyst is, require supplementary microscopic information to remove ambiguity in the deduction of a catalytic mechanism.
Abstract: A more complete understanding of the structural and mechanistic details of a catalyzed heterogeneous reaction leads both directly and indirectly to the development of new and better catalysts. For catalyst technology, the most sensitive probe of catalysts performance will continue to be the rate and selectivity of a chemical reaction. However, these macroscopic observations, adequate for determining how good a catalyst is, require supplementary microscopic information to remove ambiguity in the deduction of a catalytic mechanism. This information, almost down to the atomic level, concerning the structure and reactivity of the intermediates, the nature of adsorption sites (and sometimes the active sites) and their number, is the main objective of the science of catalysis. The most promising approach to this problem is the use of suitable probe molecules for the quantitative titration of site density and qualitative characterization of their nature by means of surface spectroscopies of the chemisor...
40 citations
TL;DR: In this paper, a review of catalytic reactions involving metal or metal cations incorporated into ion-exchange resins is presented, including polystyrene sulfonic acid (PSSA) and polyfluorinated exchange polymer (PFIEP).
Abstract: There have been a paucity of reports dealing with catalytic reactions involving metal or metal cations incorporated into ion-exchange resins. It is the objective of this review to summarize these reactions and to discuss in detail one such resin, a perfluorinated Exchange polymer, PFIEP. here survey two resin types, polystyrene sulfonic acid (PSSA) and PFIEP or Nafion [11. Acid catalysis by ion-exchange resins, in particular PSSA, has briefly been reviewed by Sherrington.
33 citations
TL;DR: In this article, the problem of multiphase nuclear reaction is addressed to achieve effective mass and heat transfer as well as a mixing pattern favorable to the particular process, and the various design and modeling aspects of these reactors have bee studied.
Abstract: Multiphase reactors involving gas, liquid, and solid phases have several important applications in the chemical industry, particularly in catalytic processes. Some of the well-known examples are: hydrogenation and oxidation of organic compounds, hydro-processing coal-derived and petroleum oils, Fischer-Tropsch synthesis, and methanation reactions. Due to the presence of three phases, the problem of reactor design is often important to achieve effective mass and heat transfer as well as a mixing pattern favorable to the particular process. The reactors are mainly of two types: (a) solid catalyst is suspended either by mechanical agitation or gas-induced agitation and (b) solid catalyst is in a fixed bed with concurrent or countercurrent feed of gas and liquid re-actants. The reactor types conventionally used in industry are: (a) mechanically agitated or bubble column slurry reactors and (b) trickle-bed or packed-bed bubble reactor. The various design and modeling aspects of these reactors have bee...
17 citations