Secondary catalysts

Baker, E. Mudge, L. Brown, M., Steam gasification of biomass with nickel secondary catalysts. Industrial and Engineering Chemistry Research 1987, 26, 1335-1339. 

Empath maintains ten object classes. Landmarks indicate a general area of the chart where a particular metabolism occurs. Compounds are primary reactants and products. Cofactors are additional reactants and products that usually drive steps energetically. Enzymes are the primary catalysts of steps most of them have an associated EC number. Agents are secondary catalysts, usually metal ions. Regulators are substances that enhance or suppress a particular reaction. Steps are reactions that include aU of the above object types. Pathways are sequences of life essential steps or steps that occur across all species. Diseases as well as Notes are associated with steps. Abbreviations are a separate category for abbreviated names on the chart and have a link to the area of primary synthesis. 

The system ESKA (Expert System for Selection and Optimization of Catalysts [20]) was designed at BASF specifically for hydrogenation reactions. The main component of a catalyst is proposed on the basis of activity patterns which describe the applicability of catalysts for different types of hydrogenations. The system also is able to propose secondary catalyst components and, if necessary, a support material which is stable under reaction conditions and does not have any undesired catalytic properties. Based on heuristics for required as well as undesired side reactions and for different catalytically active components, the system also proposes reaction conditions as temperature, pressure, the solvent or the pH. 

Secondary catalyst None None NitSlAI SiAl... 

However, with the use of palladium on activated coal, the formation of compound [9] was accomplished. As shown in entries 7 and 8 (Table 6), the combination of Pd on activated coal and acetic acid (as secondary catalyst) was not very successful. If Pd on activated coal in methanol at room temperature and a hydrogen pressure... 

Numerous catalysts have been tested for their tar destructive activity over a broad range of conditions, and recent literature reviews are available on biomass gasification tar destruction and the preparation and characterization of the various catalytic materials used for this purpose [28, 50]. These include commercial Ni catalysts developed specifically for steam reforming, which have found application in biomass gasification tar conversion and as secondary catalysts in separate fixed and fluidized bed reactors [2]. 

Soft alloy and plastics screws may be locked with anaerobics but the softness of the material will reduce the prevailing torque. If a plastics screw is being placed in a plastics part then a secondary catalyst will be needed in addition to the anaerobic composition. This will normally be an aerosol-based primer or, for large batch quantities, total immersion in the primer may be practicable. 

For the whole family, 100 per cent liquid-to-solid conversion occurs by radical polymerisation of the vinyl group of the acrylic ester, a reaction catalysed by metal and inhibited by atmospheric oxygen. Typically, therefore, the adhesives cure only when the treated parts are assembled and air is excluded from the mating surfaces. The cure rate on non-metallic surfaces is generally too low for normal commercial use and here a secondary catalyst in the form of a surface primer is beneficial. With closely fitting parts, one metal surface is usually sufficient catalyst and when both surfaces are metallic, polymerisation is rapid at room temperature. Normally, components may be handled between five and twenty minutes after assembly with full strength after at least an hour - possibly very much longer with some materials. 

Anaerobics are compatible with all metals some, such as copper, accelerate curing while others, such as zinc, may reduce the cure rate of some types and may necessitate the use of a secondary catalyst or primer. Performance falls off with softer and more ductile metals and alloys and particularly on plastics parts. Anaerobic compositions attack solvent-sensitive plastics and should not be used on them, nor are they intended for use with rubbery materials. 

In 2009, Bella et al. reported a formal [4 + 2] cycloaddition of substituted atylacetaldehydes and 2-cyclohexen-l-one which was promoted by a chiral thiazolidine catalyst and chiral quinine via enamine formation and spontaneous intramolecular aldol reaction (Scheme 2.4). The stereoselection depended upon the secondary amine catalyst, whereas the secondary catalyst was involved in the enhancement of the nucleophilicity of the derived enamine, probably through deprotonation of the carboxylic group. There... 

Figure 3.12 Relative Melt Index potential (RMIP) vs secondary catalyst activation temperature. RMIP is the melt index of the polyethylene sample normalized by the Melt Index of the standard Phillips catalyst containing 1 wt% Cr and activated with one thermal treatment in air at 870°C. Melt Index is inversely proportional to polymer MW. Reprinted from [12] with permission from Elsevier Publishing.

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