Features of the Isobutane Alkylation with Butylenes on Zeolite Catalysts
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RGANIC SYNTHESIS AND INDUSTRIAL ORGANIC CHEMISTRY
Features of the Isobutane Alkylation with Butylenes on Zeolite Catalysts I. M. Gerzelieva,*, V. A. Temnikovaa, Z. A. Saitova, and A. L. Maximova a
A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, 119991 Russia *e-mail: [email protected] Received September 7, 2020; revised September 25, 2020; accepted September 28, 2020
Abstract—Isobutane alkylation with olefins is an important process to produce a high-octane component of gasoline (alkylate) obtained using mineral acids as catalysts. Solid catalysts based on zeolites are a promising alternative to acids, but their rapid deactivation makes it difficult to implement the technology on an industrial scale. In this work, we investigated the CaLaHPtX catalyst based on molded NaX zeoliste. Physicochemical analysis of the catalyst (the residual concentration of Na2O is less than 1 wt %, acidity 1452 μmol of NH3/g, and IR-Fourier spectroscopy data with the presence of bridging OH-groups at aluminum atoms with absorption bands at 3657 and 3603 cm–1) suggest good catalytic properties. Alkylation of isobutane with butylenes was carried out on a pilot plant according to a new principle - in a “structured” mode, which guarantees a high isobutane/butylenes ratio in the reaction zone. Under these conditions, the catalyst operates for at least 24 h with stable performance (butylenes conversion – 97.1 wt %, alkylate yield – 94.1 wt %, selectivity to trimethylpentanes – 76.4 wt %). It was shown that before the catalyst is regenerated, it is necessary to stop the reaction before its activity begins to decrease in order to exclude the accumulation of hard-to-desorb deposits on its surface. The combination of alkylation in the “structured” mode and the CaLaHPtX catalyst promote a long-term reaction without reducing the quality of the alkylate for at least 5 cycles of reaction - reductive regeneration - reaction. Keywords: heterogeneous catalyst, type X zeolite, alkylation of isobutane with butylenes, structured mode, high octane component, reductive regeneration, industrial applications DOI: 10.1134/S107042722010146
INTRODUCTION Isobutane alkylation with olefins in the oil refining industry is an important process for obtaining highoctane components of gasoline—alkylate [1]. Alkylate is characterized by low saturated vapor pressure, high octane number, practically does not contain sulfur, oxygen, nitrogen, olefins and aromatic hydrocarbons; therefore, it is used as a valuable additive to commercial gasoline. In the industry, the process is carried out using sulfuric or hydrofluoric acids as a catalyst. The use of acids is associated with the complexity of operation, corrosion of equipment, the danger of transportation, the need for cleaning systems for the finished product and disposal of waste acids, which leads to additional economic costs [2, 3].
Zeolites and catalysts based on them are characterized by a homogeneous pore structure, the possibility of simple modification and are used in industry in
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