A one-step synthesis method of durene directly from syngas using integrated catalyst of Cu/ZnO/Al2O3 and Co-Nb/HZSM-5

In recent years, the demand for durene has been increased as the raw material of polyimide. However, traditional synthesis methods of durene require a large number of steps with lower efficiency. In this study, a novel synthesis method of a bifunctional integrated catalyst had been utilized, in which the methanol synthesis catalyst Cu/ZnO/Al2O3 (CZA) and the aromatization catalyst Co-Nb/HZSM-5 were combined, to synthesize durene from syngas in one step. Syngas was converted to methanol and dimethyl ether (DME) followed by the production of different aromatics with a high concentration of durene through the shape selectivity of zeolite. The optimal reaction conditions of 330 degrees C, 4 MPa, 200 h(-1), 3% Co loading, CZA/HZSM-5 = 3:2 and a unique pseudo-physical coating (PC) integrated method were applied to increase durene selectivity up to 39.71% in aromatics. Different techniques such as XRD, BET, XPS and NH3-TPD were employed to characterize different catalysts, and a variety of experiments were proceeded to compare different routes of methanol and FT synthesis. These results explain that the high selectivity of tetra-methylbenzene (tetra-MB) was due to the alkylation of trimethylbenzene (tri-MB) induced by methanol on HZSM-5 surface. This work demonstrated that the integrated catalyst could be advantageous for direct conversion of syngas to tri-MB and finally to the desired durene and it would open up the new avenues in future perspectives. (C) 2019 Elsevier Ltd. All rights reserved.