Effective Inclusion of ZnMg in a Fe-Based/HZSM-5-Integrated Catalyst for the Direct Synthesis of Aromatics from Syngas

Abstract

Being a significant raw material to numerous chemicals, aromatic hydrocarbons have been emerged as an advancing research platform in recent years, via the syngas to aromatics (STA) process. In the current study, a modified FeZnMg catalyst prepared by a sol-precipitation method was integrated with an HZSM-5 catalyst for the direct aromatic synthesis from syngas. Various catalytic/process parameters, including catalyst loading amount, precipitating pH, calcination/reduction/reaction T, space velocity, syngas ratio, reaction P, and reduction time, contributed toward the different synergism of the bimetallic Fe oxide nanoparticles. The significant electronic modulations induced upon the effective inclusion of Zn in a feasible parametric influence led to the generation of spinel (ZnFe 2 O 4 ) ferrite that eventually facilitated the reduction process of Fe oxide. While the enhanced dispersion of active sites and tuned Fe-lattice structures with Mg addition improved the carburization behavior of Fe species in response to the stronger C−O chemisorption, and thereby suppressed the excessive CO 2 and C 1 −C 4 paraffin generation. The originated synergistic interaction of bimetallic species in an appropriate catalytic environment of FeZnMg for accelerating the formation of Fe carbide, dictate the 52% aromatic selectivity at 97% CO conversion. While an excess in the Zn−Mg loading amount, pH, and calcination/reduction/reaction, T, can adversely affect the catalytic activity to varying degrees of the diminished active catalyst surface and inhibit CO adsorption.