Targeted Synthesis of Durene from CO2 via a Tailored Coupling Reaction Pathway

A precisely engineered coupling reaction pathway was developed over a rationally designed multifunctional oxide-zeolite catalyst for the highly selective transformation of CO2 to durene (1,2,4,5-tetramethylbenzene, termed 1,2,4,5-TeMB), a high-value-added aromatic compound. The detailed reaction pathway and dynamic structure evolution of the catalyst were unveiled through in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), resonant Auger electron spectroscopy (RAS), in situ X-ray absorption fine structure spectroscopy (XAFS), and density functional theory (DFT) calculations. An optimal oxide catalyst featuring the tetragonal InZrOx solid solution structure was developed to match the thermodynamic characteristics of the CO2-to-aromatics reaction. It exhibits a spatial synergy between CO2 adsorption and H2 activation, therefore promoting CO2 hydrogenation via the HCOO* pathway at lower temperatures, which is thermodynamically essential for the formation of TeMBs over zeolites. For the selectivity control among several TeMB isomers, a ZSM-5 nanosheet zeolite with a b-axis dimension of subhundred nanometers was optimized. The presence of abundant surface acid sites and pore mouth confinement in these ZSM-5 nanosheets reinforces the pore mouth shape-selective methylation and precisely positions methyl substituents on benzene rings. Through efficiently coupling reaction processes of low-temperature CO2 hydrogenation, aromatization, and zeolite pore mouth shape-selective methylation, the InZrOx/ZSM-5 catalyst substantially narrows the C6-C12 aromatic distribution and achieves the targeted synthesis of durene, which accounts for 83.3% of the total aromatic products.