Comparison of fibrous versus Cu/ZnO/Al 2 O 3 catalyst for CO 2 hydrogenation to methanol through modeling the reactor and the process flowsheet

Methanol is a promising alternative for the energy transition towards a carbon-neutral economy as it can be produced by CO 2 hydrogenation. Several studies reported in the literature regarding mathematical modeling of CO 2 hydrogenation consider the conventional Cu/ZnO/Al 2 O 3 catalyst, despite the observed deactivation of catalyst particles under a CO 2 -rich atmosphere. Although some studies showed that the Cu/ZnO/Al 2 O 3 /ZrO 2 fibrous catalyst presented better performance than the conventional catalyst for CO 2 hydrogenation, the literature still lacks a systematic comparison of the influence of the fibrous catalyst over the conventional catalyst on the process performance. This paper compares both catalysts using a mathematical model of the one-pass reactor and the integrated process flowsheet, which considers recycling. The results for the one-pass simulation show that the fibrous catalyst provides better CO 2 conversion and selectivity, even at lower temperatures, higher CO 2 partial pressure, and lower space–time velocity. The role of CO in the methanol synthesis with the fibrous catalyst is further highlighted, unlike for the conventional catalyst. The simulation of the complete flowsheet with recycle streams shows the benefits of using the fibrous cataly. It affords significant catalyst savings while achieving much higher conversions than the conventional catalyst.