Catalytic specificity

Abstract

SCOPECatalytic specificity refers to the particular ability of a substance or closely related group of substances to catalyze a given type of chemical transformation. Identifying the type of catalyst which is good for a particular reaction is a matter of great practical importance. In the area of heterogeneous catalysis, to which this review is limited, there are few, if any, examples where the factors determining catalytic specificity are understood in detail. However, much progress has been made in establishing patterns of variation in catalytic behavior from one substance to another for various types of reactions. In particular, broad relationships are often evident between the catalytic activity of an element or its compounds and the position of the element in the periodic table. These relationships introduce a measure of order into heterogeneous catalysis and will be useful in the development of a more fundamental understanding of the subject.The present review considers a variety of classes of reactions from the standpoint of assessing patterns of variation in behavior among catalysts. The types of reactions considered include hydrogenation, hydrogenolysis, isomerization, ammonia synthesis and decomposition, oxidation, and the decomposition of alcohols and organic acids. Relationships between catalytic activities and the chemisorption properties of reactants are discussed repeatedly. Both metal and oxide type catalysts are considered. However, most of the emphasis is on metals, for which more extensive data comparing specific catalytic activities are available.

Catalytic C(1), C(2)‐Bond Cleavage of Long‐Chain Aliphatic Alcohols and ω‐Phenylalkyl Alcohols

“…Experiments carried out with Cu/Ni catalysts of different composition showed that there is a remarkable decrease of (C, C)-bond attack with increasing Cu content, whereas it seems that the (C, H)-bond attack is not strongly influenced by the Cu content. Similar observations have been reported in other reactions [14] [15]. During the reaction of benzyl alcohol considerable catalyst poisoning was observed.…”

Heterogeneous Catalysis: Some Recent Developments

“…646 and electrical self-stimulation of the brain (13,14). The seemingly ubiquitous nature of catecholamine involvement across a wide spectrum of behaviors and the remarkable adaptive capacity of catecholamines to maintain relatively normal function even in cases of severe damage (1), suggests that catecholamine systems may play a very fundamental role in mediating the interaction between the organism and its environment.…”

“…An extremely important feature of heterogeneous catalysis is specificity in relation to the chemical constitution of a surface (14,15). The hydrogenolysis of alkanes provides an excellent example of specificity in catalysis by metals.…”

Impact of Hydrogenolysis on the Selectivity of the Fischer–Tropsch Synthesis: Diesel Fuel Production over Mesoporous Zeolite‐Y‐Supported Cobalt Nanoparticles

“…[2b,10] Thes uccessive demethylation at the terminal CÀC bond is known to occur for cobalt-based catalysts,t hus forming CH 4 and aheavier fragment. [10,11] Thedistributions of the products from n-hexadecane over the catalysts without Brønsted acidity (Table 2a nd Figure S3) suggest ah ydrogenolysis mechanism. Although the addition of Na + onto the Co/SiO 2 decreased its activity for hydrogenolysis (see Table S4), the Co/Na-meso-Y catalyst with Na + in the cation-exchange position showed high hydrogenolysis ability.…”

“…Extensive studies have been devoted to developing efficient catalysts for FT synthesis, [1] but the effective control of product selectivity remains one of the grand challenges.T he FT products generally follow the Anderson-Schulz-Flory (ASF) distribution, which is unselective for the middle-distillate products. [1b] Fore xample,t he selectivities of products in gasoline (C [5][6][7][8][9][10][11] and diesel (C 10-20 )f ractions are limited to 45 and 39 %, respectively.Conventionally,the FT products are subjected to further hydrotreatment to increase liquid fuel selectivity. Compared to this two-stage process,the direct production of specific-range liquid fuels would be more energy and cost efficient.…”