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The conversion of light paraffins to olefins and the secondary reactions of the unsaturated compounds were investigated on H-ZSM5 and H-Y zeolites between 733 and 823 K. Steady stateand transient response-isotope tracing studies revealed that two mechanisms of dehydrogenation are operative. The main pathway is represented by monomolecular, protolytic dehydrogenation. This reaction contributes most to steady state olefin production. Additionally, at the initial stages of the reaction, extra framework aluminum moieties are speculated to participate in high dehydrogenation activity. This pathway is blocked at later stages of the reaction by product (hydrogen) inhibition. The intrinsic rates of protolytic dehydrogenation and olefin desorption range in the same order of magnitude. At high protolytic dehydrogenation rates, olefin desorption represents the rate determining step. Depending on the process conditions, olefins undergo secondary cracking, oligomerization, or isomerization. The latter proceeds via intramolecular rearrangement, possibly via a cyclopropylcarbenium ion at high temperatures and low conversions. At reaction conditions where bimolecular cracking prevails, isomerization is concluded to occur via secondary cracking of di-or oligomers.

Time-resolved FTIR microscopy was used to investigate in situ the transport and sorption of toluene in individual ZSM-5 crystals with varying degree of perfection. The results indicate that the rate of transport of toluene in the pore system of zeolite ZSM-5 strongly depends upon the degree of crystal intergrowth. The diffusion coefficients observed with single crystals were 3 orders of magnitude higher than the diffusion coefficients measured for a polycrystalline sample. The first results of this new method to study diffusion in microporous materials are compared to the results from other techniques.

Steady-state isotope tracer studies and isotope transient response experiments of n-butane conversion on H-ZSM-5 (Si/Al = 35) were carried out between 673 and 823 K. Among the three main reactions, the rate of H/D-exchange is at least one order of magnitude higher compared to the rates of cracking or dehydrogenation. Its apparent energy of activation is lower than that of the latter two processes. The rates of H/D-exchange are higher for larger molecules than for smaller ones and faster with olefins than with paraffins. Proton exchange proceeds stepwise, i.e., only one hydrogen (deuterium) of the substrate is exchanged with one deuterium (hydrogen) in a single catalytic turnover. A kinetic isotope effect was found for protolytic cracking, but not for dehydrogenation. Protonation of the feed (deprotonation of the zeolite) is concluded to be involved in the rate determining step of cracking.

The conversion of light linear and branched alkanes on two faujasite samples containing different concentrations of free Brcnsted acid sites and extraframework alumina (EFAL) was studied between 733 K and 813 K. Protolytic cracking and bimolecular hydride transfer proceeded solely on BrCnsted acid sites. For cracking of n-alkanes, the variation of the concentration of extraframework aluminum did not affect the catalytic activity per accessible BrCnsted acid site. The activity to dehydrogenation is enhanced in the presence of EFAL and, unlike protolytic cracking, it decreased with time on stream. At high conversions relatively high concentrations of olefins change the selectivity and decrease the turnover frequencies. Compared to n-alkanes, the catalytic activity to convert iso-alkanes is enhanced in the presence of extralattice alumina.

The article contains sections titled: 1. Introduction 1.1. Catalysts 1.1.1. Acidic Catalysts 1.1.2. Basic Catalysts 1.1.3. Organometallic Catalysts 1.2. Alkylating and Acylating Agents 1.3. Mechanism 1.3.1. Alkylation 1.3.2. Acylation 2. Alkylation and Acylation of Aromatic Compounds 2.1. Alkylation 2.1.1. Alkylation of Benzene 2.1.2. Cycloalkylation 2.1.3. Alkylation of Substituted Benzenes 2.1.4. Alkylation of Phenols 2.1.5. Alkylation of Aromatic Amines 2.1.6. Alkylation of Heteroaromatic Compounds and Related Substrates 2.1.7. Miscellaneous Alkylation Reactions 2.2. Acylation 2.2.1. Acylation of Benzene and Benzene Derivatives 2.2.2. Acylation of Polynuclear Aromatic Compounds 2.2.3. Acylation of Heteroaromatic Compounds 2.2.4. Acylation of Nonbenzenoid Aromatic Compounds 2.2.5. Miscellaneous Acylation Reactions 3. Acylation and Alkylation of Aliphatic Hydrocarbons 4. N ‐Alkylation and N ‐Acylation 4.1. N ‐Alkylation 4.1.1. N ‐Alkylation by Alcohols or Ethers 4.1.2. N ‐Alkylation by Alkyl Halides 4.1.3. N ‐Alkylation by Olefins 4.1.4. N ‐Alkylation by Carbonyl Compounds (Reductive Alkylation) 4.2. N ‐Acylation 5. O ‐Alkylation and O ‐Acylation 5.1. Synthesis of Esters 5.2. Synthesis of Anhydrides 5.3. Synthesis of Ethers 6. CH ‐Alkylation and CH ‐Acylation of Nonaromatic Compounds 7. Synthesis of Metal Alkyls

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