Enhanced conversion of syngas to high-quality gasoline hydrocarbons over ZnZrOx coupled SAPO-11 nanosheets bifunctional catalyst

Abstract

Syngas is a key precursor for synthesizing gasoline (C5-C11) hydrocarbons, offering an efficient route for utilizing non-petroleum carbon sources. However, the conventional Fischer-Tropsch synthesis (FTS) process faces a constraint with a maximum 45% selectivity for C5-C11, attributed to the Anderson-Schultz-Flory (ASF) distribution. Herein, bifunctional catalysts comprising ZnZrOx with different Zr/Zn ratios along with SAPO-11 zeolite sieves featuring varied morphologies like nanosheets (SA-A), petals (SA-B), and spheres (SA-C) have been effectively formulated and employed for the syngas-to-gasoline hydrocarbons (STG) reaction. Notably, the selectivity toward C5-C11 far exceeded the ASF limits. Under identical reaction parameters, the Zn1Zr4Ox/SA-A catalyst demonstrated notable enhancements of 6.6% and 26.2% in CO conversion, along with 4.6% and 7.6% increases in C5-C11 selectivity, as compared to that of Zn1Zr4Ox/SA-B and Zn1Zr4Ox/SA-C catalysts, respectively. Furthermore, under the ideal conditions (380 °C, 4.5 MPa and gas hourly space velocity (GHSV) of 2400 mL min−1 g−1), Zn1Zr4Ox/SA-A exhibited an exceptional C5-C11 selectivity of 69.8% (CO2-free) alongside a single-pass CO conversion of 30.4%. Impressively, isoparaffin constituted 39.2% of the total composition, with the iso/n-paraffin ratio reaching 11.8. Even after 100 h, the catalyst maintained its remarkable catalytic activity, with the CO conversion and C5-C11 selectivity maintaining levels of 27.5% and 66.85%, respectively.