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Joint conversion of the propane–butane fraction of gaseous С3–С4 alkanes and straight-run naphtha by involving them in the joint isomerization–disproportionation process on Ме/Н–N–SO42–/ZrO2 composite catalytic systems, where N is MOR or MFI zeolite or Al2O3, was studied at atmospheric pressure in the interval 160–240°С. The catalyst of the composition 0.4Со/HZSM-5/SO42– (2.0)–ZrO2 at 180°С allows up to 63.5% of gaseous C4– alkanes to be involved in isomerization–disproportionation processing of the mixture of straight-run naphtha and propane–butane fraction (1 : 1 by weight), the content of C5–C6 alkanes in the catalyzate to be increased by 21.4%, and the relative content of their branched isomers to be increased to 88.8%. The effect of hydrogen on the conversion of С4– and С8+ components of the mixture of straight-run naphtha and propane–butane fraction (1 : 1 by weight) was studied; an increase in the Н2/hydrocarbon ratio from 2 to 4 leads to an increase in the conversion of С4– alkanes from 63.5 to 90%. The possibility of expanding the resources for producing С5–С6 alkanes with increased content of high-octane branched components by joint processing of the propane–butane fraction and straight-run naphtha was demonstrated.

The conversion of straight-run naphtha on composite catalytic systems containing HZSM-5 zeolite modified with 0.4 wt % Co or Ni and 15% SZ (10% SO 4 2- /ZrO2), performed at atmospheric pressure in the interval 140–200°C, was studied. At 140–200°C, the major products of straight-run naphtha conversion are branched C5−C6 alkanes. At T ≥ 180°C, the reaction products become enriched in gaseous alkanes. Analysis of the conversion products suggests that the process occurs via formation of a skeleton-isomerized intermediate, followed by its cleavage (disproportionation) at the β- or α-bond. The conversion is influenced by the conditions of the reaction and reduction of the composite catalytic system. On the Co-containing composite catalyst reduced at 380°C, the conversion of C8+ components of straight-run naphtha at 180°C, feed space velocity of 2.5 h−1, and H2/CH = 3 is 76.8%, and the content of C5−C6 alkanes consisting to 78% of isoparaffins reaches 61%.

The conversion of n-C7H16, n-C4H10 and mixtures of C7H16: n-C4H10 = 1: 0.3 on the composite catalysts Al2O3/WO 4 2– ∙ZrO2 (A-WZ) and HMOR/ WO 4 2– ∙ZrO2 (M-WZ) at atmospheric pressure, H2/hydrocarbon = 3 and temperatures of 140-200°C was studied. It was found that a mixture of C7H16: n-C4H10 on M-WZ with high selectivity is converted into C5–C6 isomers. An assumption was made about the mechanism of the formation of the bimolecular intermediate C11, which decays earlier than occurs the formation of the products of the conversion of the mixture C7H16: n-C4H10.

The possibility of using mixtures of commercial catalysts bearing acid–base or redox sites for controlling the activity and selectivity of conversion of methanol into dimethyl ether, of these substances into desired hydrocarbons, and of low-temperature dehydroalkylation of benzene with propane was demonstrated.

Results are presented from studies of the dehydromethylation (DHM) of methylcyclohexane (MCH) and the simultaneous transformation of straight-run gasoline fractions and methanol on modified forms of mordenite and pentasil in the presence of various hydrogen acceptors (O2, CO2). High selectivity on xylene isomers is observed for polycationic modifications of HNa-TsVM. On such catalytic systems, the degrees of DHM and dehydrodisproportionation (DHD) of MCH grow with an increase in O2-to-CO2 ratio in the range of 0.05 : (1–1.5), while the degree of its dehydrogenation to toluene is virtually constant. High yields of di- and trimethylbenzenes are achieved in the reactions between methanol and gasoline fractions composed mainly of C7–C8 hydrocarbons at 100–140 °C. The results from this study can be used for straight-run gasoline reforming with the aim of increasing the yield of C8-C9 aromatic hydrocarbons.

Conversion of n-butane, methanol, and their mixture on ZSM-5 zeolite catalysts containing zinc and/or zirconium was studied, and ways were found to control the yield and ratio of major reaction products: C1-C3 alkanes, C2-C4 alkenes, C5-C7 isoalkanes, and arenes. The schemes of formation of these products were suggested.

We have studied conversion of methanol to dimethyl ether and hydrocarbons on aluminum oxide and also on H- and phosphoric acid-modified forms of zeolites Y and ZSM-5. We hypothesize that formation of the primary hydrocarbon ethylene is structure-sensitive and depends on the distance between Bronsted acid and Lewis base sites responsible for the reaction.

Results of examining the reaction of phenol with diprene, dipentene, and the isoprene cyclodimer fraction using orthophosphoric acid-impregnated zeolite Y as a catalyst in a continuous processing unit are presented. Optimal conditions for the synthesis of p-cycloalkylphenols have been found. It has been shown that under the optimal conditions, the yield of target p-cycloalkylphenols is 72.3–75.6% and the selectivity is 91.6–95.7%.

The results of studies on the oxidative dehydrogenation of 4-vinylcyclohexene to ethylbenzene and styrene and ethylbenzene to styrene on nanocomposite systems prepared by the immobilization of carbon nanoparticles on the H forms of zeolites and the modification of the resulting samples with platinum, gallium, and gadolinium are given. The activities of these catalysts are compared, and the synergism of the action of zeolite and carbon nanoparticles under the conditions of dehydrogenation is established. The immobilization of carbon nanoparticles into zeolite matrices contributes to an increase in their activity and stability and also to a decrease in the reaction temperature. The high yields of 4-vinylcyclohexene and ethylbenzene dehydrogenation products are reached at 425 and 470°C, respectively.

Comparative researches were conducted of zinc-, zirconia, and zinc-zirconia-ziolite catalysts for n-butane aromatization.

The effect of reactant-catalyst (R-C) interaction on the activation and deactivation of a 0.5 Ni, 1.0 ReOx/Al2O3 catalyst during the dehydrocyclohexamerization of methane to benzene has been studied. The R-C interaction involves partial reduction of the catalyst and the buildup of at least two forms of carbon deposit. It has been found that the catalyst activation time shortens with an increase in the amount of carbon deposit remaining after treatment with air. A comparison of the initial (3 min) and maximal (20 min of experimental run) benzene formation rates with the quantity of carbon deposit remaining on the catalyst after air treatment has shown that the carbon deposit is responsible for the subsequent oligomerization and dehydrocyclization functions of the C2Hy intermediates produced owing to oxygen bonded to the catalyst. It has been suggested that the catalyst deactivation during the reaction is associated with a decrease in the concentration of bound oxygen.

The conversion of CH4 and the C6H6—C3H8 mixture over (M, ReOx)/Al2O3 (M = Ni, Co, Pt) analogues of industrial low-octane gasoline reforming catalysts containing 0.5 wt % M in a finely divided state and 0.3–1.0 wt % Re is reported. The unreduced catalysts activate the conversion of CH4 into C6H6 at 650°C. Using (M, ReOx)/Al2O3 + HZ catalytic mixtures (HZ = H-form of zeolite Y, M, or ZSM-5), it is possible to carry out low-temperature C6H6 alkylation or C3H8 dehydrogenation at 180–350°C. These processes are aimed at involving oil refining waste into obtaining valuable hydrocarbons. The processes can be commercial- ized at low-octane reforming and gas-phase benzene alkylation plants and can be intensified by separating the resulting H2 in membrane reactors.

The oxidative dehydrogenation reaction of 4-vinylcyclohexene (4-VCH) in the presence of a pentasil zeolite (TsVM) modified by platinum, gallium, gadolinium, and potassium was investigated. The influence of the nature of the modifiers on the progression of the reaction and the yields of the desired product, ethylbenzene and styrene, was established. It was found that the conversion of 4-VCH into ethylbenzene and styrene proceeds along two parallel routes, the oxidative dehydroisomerization and dehydrogenation of the reactant hydrocarbon. Conditions for the maximal yield of styrene on potassium hydroxide-promoted Pt,Ga,Gd/HNa-TsVM were determined.

The conversion of C6H6: C3H8C mixtures on mixed catalysts composed of the metal catalysts Pt,ReOx/Al2O3 and zeolites Y, M, and ZSM-5 in the H form was studied. The products of benzene dehydroalkylation by propane and propane dehydrogenation products are formed at 180–350°C. It has been shown that propane is activated on the metal catalysts and C6H6 interacts with the zeolites yielding the C6H7+ intermediate, which acts as an agent of proton transfer from a zeolite to a metal catalyst, and another intermediate C9H13+ (I). Cumene, alkylbenzenes, and propene are formed as a result of the conversion of I. A comparison of the results of the conversion of these mixtures on the composite catalysts with different zeolites shows that the formation of cumene and propene is thermally controlled and the formation of the other products is kinetically controlled. It has been concluded that the coupling of the redox properties of the metal catalysts with the acid-base properties of the zeolite catalysts facilitates the low-temperature transformations of the mixtures.

The results of phenol aralkylation with components of the 130–170°C fraction of pyrolysis products on zeolite impregnated with orthophosphoric acid in a flow reactor are presented. The optimal conditions of p-aralkylphenol synthesis have been found. Under the optimal conditions, the yield of the desired aralkylphenol was 53.6% of the theoretical value and the selectivity was 95.5%. A p-aralkylphenolamine resin was synthesized on the basis of p-aralkylphenol and hexamethylenetetramine and was tested as an antioxidant for M-8 motor oil at high temperatures.

Using high-performance catalysts prepared from zeolites Y, M, and ZSM-5, the dependence on the acid and micropore characteristics of modified zeolites was studied for the yields of products of dehydrocycloaromatization of C2+ alkanes, the isomerization of n-pentane, and the disproportionation of toluene. On the basis of the obtained experimental results and published data, it was shown that the initial activation of reactant molecules occurs on acid sites regardless of their acid strength and that the formation and rearrangement of C-C bonds are controlled by the molecular-sieve parameters of a zeolite and can be varied via the modification of the virgin zeolites used to prepare the catalysts.

Aromatization of light hydrocarbons (propane, butane, propane-propene mixture, and cat-cracker off-gases) on ZnO-zeolite and lanthanide-zeolite catalysts based on zeolite TsVM (SiO2/Al2O3 = 62) and industrial catalyst SGK-1 was studied. It was shown that the modification of catalysts with lanthanides leads to an increase in both the total yield of xylenes and the p-xylene selectivity, a change that is explained by the formation of branched intermediates and steric specifics of their further conversion.

The possibility of increasing the yield of target products and para-selectivity of toluene disproportionation on modified zeolites by optimization of their microporous structure was studied.

Interaction of benzene with propane (C6H6:C3H8=1:9) was studied at 453–623 K in the presence of acidic HY-zeolite Pt, Re/Al2O3 bimetal alumina catalysts (APRC), and mixed (50% APRC+50%HY) catalyst (mixed catalyst, MC) systems with Pt and Re content 0.3 and 0.5%, respectively. Unlike inactive separate components, MC activates benzene dehydroalkylation (DHA) by propane even at 453 K to form isopropylbenzene (IPB) and hydrogen. Increased temperatures lead to the formation of additional products, such as propene (at 523 K) and other alkylbenzenes (at 573 K). Activation of benzene–propane mixture is characterized by an induction period prior to the formation of conversion products. MC treatment by ammonia at 423 K leads to increase of selectivity of IPB formation. The mechanism of low-temperature DHA of benzene over MC has been proposed.

Diffuse reflectance IR spectroscopy along with H2 and CO adsorption measurements were applied to the study of 0.3% Pt/-γ-Al2O3 catalyst precalcined in an air flow at 1023 K and then reduced at 773 and 973 K in hydrogen. Reduction of the catalyst at 973 K results in formation of supported metallic Pt particles in SMSI (strong metal-support interaction) state, as evidenced by the sharp decrease of Pt ability to chemisorb H, at room temperature as well as the significant lowering of thermal stability of linear Pt-CO complexes. Spectroscopically the effect of SMSI is manifested by the slight increase of the singleton frequency of linearly adsorbed CO from 2050 to 2060 cm−1 together with the decrease of the dipole-dipole shift from 40 to 15 cm−1 and by a large decrease of absorption band extinction.

The effect of oxidative-reductive pretreatment of Re−Al−O catalysts on their activity in methane aromatization has been established. Paramagnetic centers have been identified and their contribution to the conversion of methane into benzene over these catalyst is discussed.

The conversion of C6H6:C3H8 mixtures over mixed catalysts (MC) consisted of zeolite HY, HM or H- ZSM-5 and Pt, Re-Al2O3 (Pt-0.3 wt %; Re-0.5 wt %) has been studied. Propane has been found to be dehydrogenated to propylene even at 523K by participation of benzene as an astoichiometric component of reaction. Using the data obtained on dependence of propylene and isopropylbenzene yields on experiment conditions the assumption on common intermediate preceding the formation of these products has been made. The thermodynamically unfavourable reactions of benzene dehydroalkylation by propane and dehydrogenation of propane are explained by appearance of conjugated redox-acidic-basic interaction due to proton cyclic transfer between zeolite and partially reduced sites of metal component of MC and alternative oxidation and reduction of these sites.

Publisher Summary This chapter discusses benzene alkylation by propane using a zeolite-containing catalyst. The isopropylbenzene formation is shown to begin at 180–350°C over HY and platinum (Pt), rhenium /alumina (Re/Al 2 O 3 ) admixed catalysts. The temperature increase leads to cyclopropane (C 3 H 6 ) (250°C) and other alkylbenzenes (300°C) formation. The byproducts may be reduced by the selective poisoning of Bronsted acidic centres by ammonium. From the considerations on the reaction, the probable mechanism of benzene dehydroalkylation by propane has also been proposed.

Publisher Summary This chapter presents study on the adsorptive and catalytic properties of zeolites HY, HZSM-5, and HM (natural and synthetic) subjected to dealumination, ion exchange with rare earth, and transition elements. The changes in conversion and selectivity for m-xylene and n-pentane are connected with the changes of the zeolites microporous structure.These changes are in conformity with Dubinin–Radushkevitch (DR) equation parameters. The DR equation could be applied to the simple test method elaboration of the starting and modified zeolites microporous structure through their adsorptive properties.