Potential catalytic materials

Once the potential catalytic materials have been selected and synthesized, they must be tested in catalytic reactors and fully characterized by various physical, chemical and spectroscopic techniques [43]. For the case of developing catalysts with improved selectivity, an understanding of the factors controlling the selectivity... 

Deriving and applying quantitative relationships for predicting chemical and physico-chemical properties of potential catalytic materials and relating them to the energetic and dynamic interactions of reacting molecules with the catalyst surface. 

Ruthenium on a graphite or basic oxide support is also used as a catalyst in industrial synthesis. A Co-Mo-N system has also been investigated as a potential catalytic material, however, it has to be improved to compete with the aheady available catalysts." ... 

Reducible metal oxides, which are able to provide their lattice oxygen for methane activation, are potential catalytic materials for alternating feeding of CH4 and O2. Mn- and Co-based perovskites were identified as effective catalysts for such OCM operation [24]. At best, the yield of C2 hydrocarbons of 20% with the corresponding selectivity of 73% was obtained at 1073 K over S1C0O3 doped with the oxides or hydroxides of K and Na applying a 1.5-min cycle of methane. However, the catalyst productivity remained still low. 

The task of finding, for a given set of potential catalytic materials, a subset of representatives conveying the required information about the whole set has for nearly a century been addressed by methods of statistical design of experiments (DOE). A very simple kind called factorial design is used if the required information represents the impact of any combination of possible values of some n independent factors. If... 

Bosch and co-workers devised laboratory reactors to operate at high pressure and temperature in a recycle mode. These test reactors had the essential characteristics of potential industrial reactors and were used by Mittasch and co-workers to screen some 20,000 samples as candidate catalysts. The results led to the identification of an iron-containing mineral that is similar to today s industrial catalysts. The researchers recognized the need for porous catalytic materials and materials with more than one component, today identified as the support, the catalyticaHy active component, and the promoter. Today s technology for catalyst testing has become more efficient because much of the test equipment is automated, and the analysis of products and catalysts is much faster and more accurate. 

Two classes of metals have been examined for potential use as catalytic materials for automobile exhaust control. These consist of some of the transitional base metal series, for instance, cobalt, copper, chromium, nickel, manganese, and vanadium and the precious metal series consisting of platinum [7440-06-4], Pt palladium [7440-05-3], Pd rhodium [7440-16-6], Rh iridium, [7439-88-5], Ir and mthenium [7440-18-8], Ru. Specific catalyst activities are shown in Table 3. 

The potential for the use of catalysis in support of sustainability is enormous [102, 103]. New heterogeneous and homogeneous catalysts for improved reaction selectivity, and catalyst activity and stabihty, are needed, for example, new catalytic materials with new carbon modifications for nanotubes, new polymers. 

In addition, the interdigital micro mixers used have a very low inventory of catalytic material and have the potential for automation [64]. 

In the recent past the potential of zeolites in the manufacture of fine chemicals has received considerable attention. High-Si zeolites can have Hammet s acidity function Ho of -12.8 which is close to those for superacids. MCM (Mobil Catalytic Materials) have opened up new vistas due to larger pore sizes. 

It is well known that during liquefaction there is always some amount of material which appears as insoluble, residual solids (65,71). These materials are composed of mixtures of coal-related minerals, unreacted (or partially reacted) macerals and a diverse range of solids that are formed during processing. Practical experience obtained in liquefaction pilot plant operations has frequently shown that these materials are not completely eluted out of reaction vessels. Thus, there is a net accumulation of solids within vessels and fluid transfer lines in the form of agglomerated masses and wall deposits. These materials are often referred to as reactor solids. It is important to understand the phenomena involved in reactor solids retention for several reasons. Firstly, they can be detrimental to the successful operation of a plant because extensive accumulation can lead to reduced conversion, enhanced abrasion rates, poor heat transfer and, in severe cases, reactor plugging. Secondly, some retention of minerals, especially pyrrhotites, may be desirable because of their potential catalytic activity. 

Reasoning that other macrocyclic materials might also display many of the specific properties of the cycloamyloses, Hershfield and Bender (1972) prepared a macrocyclic amine containing two potentially catalytic hydrox-amic acid groups (16). The aliphatic chains of this material provide a potential binding site similar to the cycloamylose cavity (the diameter of the... 

As early as 1952, perovskites were proposed as catalytic materials for CO oxidation[55]. Twenty years later, their potential application as catalysts for automobile exhaust purification... 

The six sections following the overview chapter deal with aspects of selective oxidation that range from theories and concepts to state-of-the-art engineering applications. Several chapters describe the synthesis, characterization, and performance of potentially attractive new catalytic materials. These catalysts range from single crystals with well-defined crystal faces to highly dispersed or amorphous solids. Most of the actual catalytic reactions studied involve the oxidation of hydrocarbons in the range from to C. ... 

We report here a study of Zr, Nb, Cr, and Mo hydrocarbyl compounds grafted onto oxide supports as potential olefin polymerization catalysts and oxide-supported Mo and W 7r-allyl derivatives in olefin disproportionation catalyses. The interaction of these compounds with silica and alumina supports has been examined using ESR and IR, analyses to define the catalytic materials that result. Finally, we consider why chemical support of these organometallic compounds confers on them an enhanced catalytic activity. 

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