Coconversion of n -Dodecane and 2-Methylthiophene in the Presence of Dual-Zeolite Cracking Catalysts Containing Differen
- PDF / 371,921 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 37 Downloads / 159 Views
conversion of n-Dodecane and 2-Methylthiophene in the Presence of Dual-Zeolite Cracking Catalysts Containing Different Amounts of Rare-Earth Elements K. S. Plekhovaa, A. S. Yurtaevaa, O. V. Potapenkoa, *, T. P. Sorokinaa, and V. P. Doronina aCenter
for New Chemical Technologies, Omsk Branch, Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Omsk, 644040 Russia *e-mail: [email protected] Received March 16, 2020; revised April 1, 2020; accepted April 10, 2020
Abstract—The effect of the rare-earth element (REE) content in dual-zeolite cracking catalysts on the conversion of n-dodecane and an n-dodecane–2-methylthiophene mixture (5000 ppm S) has been studied. The catalysts have been synthesized using zeolites Y and ZSM-5 modified with REEs and phosphorus, respectively, as the active component. It has been shown that the presence of REE oxides in zeolite Y (at a constant SiO2/Al2O3 ratio) affects the catalytic activity of cracking catalysts based on this zeolite. The dependence of the light olefin yield on the REE oxide content in zeolite Y passes through a maximum at 2–3 wt %. The presence of a sulfur compound in an amount of 5000 ppm (in terms of sulfur) in the feedstock leads to a decrease in the model hydrocarbon conversion and the C2–C4 olefin yield. In the presence of a sulfur compound, the change in the C2–C4 olefin yield as a function of REE oxide content in zeolite Y is less pronounced than that in the case of individual n-dodecane cracking. Keywords: zeolite-containing catalyst, Y, ZSM-5, rare-earth elements, lower olefins, thiophene compounds, n-dodecane DOI: 10.1134/S0965544120080113
Lower olefins, such as ethylene, propylene, and butylenes, are important feedstocks for the industrial production of various polymers and petrochemicals [1]. The petrochemical industry is currently experiencing a severe shortage of propylene because of the growing demand for propylene derivatives. One of the main secondary processes of petroleum refining providing a high yield of light unsaturated hydrocarbons is the catalytic cracking of petroleum fractions [2]. Feedstocks for this process can be light hydrocarbon fractions (low-grade gasoline fractions, butane–butylene fraction), heavy petroleum fractions (vacuum gas oils), and residues of secondary conversion processes (e.g., hydrocracking residue). Catalytic cracking feedstocks are characterized by a complex group composition, which comprises paraffins, naphthenes, olefins, and aromatic hydrocarbons. The model compounds used to determine the hydrocarbon conversion routes are n-paraffins or naphthenes [3, 4]. These compounds exhibit a moderate reactivity compared with that of olefins; unlike arenas, they can act as hydrogen donors; this feature makes it possible to determine the ratio between cracking and hydrogen transfer reactions. In addition, the feedstock composition includes heterorganic and organometallic compounds, which
affect the distribution of cracking products [5–9]. Sulfur-containing compounds are the most abundant heteroatomic compoun
Data Loading...
