Year: 2023
Type: article
Abstract: The direct synthesis of light olefins from syngas via Fischer-Tropsch synthesis reaction is a promising technology for direct synthesis of olefins from syngas.The key is to improve the selectivity of light olefins through the regulation of product distribution.In this work, the hydrophobic Fe@Si catalyst was prepared by room temperature solid state method-Stöber-silylation method, and then the catalyst was combined with SAPO-34 molecular sieves with different contents to prepare Fe@Si/S-34 composite catalysts.The effects of SAPO-34 molecular sieve content on the physicochemical properties of the catalysts were investigated by X-ray diffraction, scanning electron microscopy, N2 adsorption-desorption, NH3 temperature programmed desorption and water contact angle measurement.The results showed that the content of SAPO-34 molecular sieve has significant influence on the surface area, pore volume, acidity and hydrophobicity of the catalysts.With the increase of SAPO-34 molecular sieve content, the specific surface area and total pore volume of the catalyst increased, the weak acid and medium-strong acid sites increased, and the hydrophobicity weakened.The catalytic performance evaluation results showed that the Fe@Si/S-34 composite catalyst decomposed C5+ hydrocarbons into light hydrocarbons, significantly reduced the selectivity of C5+ products and increased the selectivity of C2～C4 hydrocarbons.Appropriate SAPO-34 molecular sieve could significantly improve the selectivity of C2～C4 olefins.When the mass ratio of Fe@Si catalyst to SAPO-34 is 2, the C2～C4 olefin selectivity of Fe@Si/S-34 catalyst is the highest, the conversion of CO is 80.0%, the selectivity of CO2 in the product is 8.9%, and the selectivity of C2～C4 olefins is 31.1%.In this study, the hydrophobicity of Fe@Si catalyst and the cracking activity of SAPO-34 molecular sieve for C5+ hydrocarbon were coupled together to inhibit the water-gas shift (WGS) reaction, reduce the CO2 selectivity and obtain higher C2～C4 olefin selectivity, which provided a new strategy for the development of catalysts for Fischer-Tropsch synthesis to olefins.
Source: 化学学报
DOI: 10.6023/a22070329
Institution: Xi'an University of Science and Technology
Language: English
Subfield: Catalysis
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: bronze
Awards: 核壳结构梯级功能加氢脱硫催化剂的构筑及催化机制研究, G754777528
OpenAlex ID: W4319600467