In2O3-ZrO2 as Alternative to Cu-based Catalysts for Methanol Production Step in the CO2 to Hydrocarbon Process

Abstract

As a consequence of the increasing greenhouse gas emissions, CO₂ valorization processes are gaining importance in the last decades. Amongst the most attractive processes for CO₂ utilization, its conversion into hydrocarbons stands out, in particular by means of catalytic processes with syngas co-feeding. With this purpose, an In₂O₃-ZrO₂ (InZr) catalyst alternative to the traditional Cu-ZnO-ZrO₂ (CuZnZr) for methanol synthesis (as the first stage of the direct synthesis of hydrocarbons from CO₂/CO hydrogenation) was assessed. Afterwards, both catalysts were tested in tandem with HZM-5 zeolite for the production of fuel-range hydrocarbons. The catalysts were characterized by several techniques and ascertained by means of reaction runs at different operating conditions, aiming to assess the effect of temperature on the performance. Even if CuZnZr resulted in higher methanol production, InZr catalyst proved to be the most adequate catalyst for the integrated process, since CuZnZr sintered at temperatures above 300 ºC (needed for the conversion of methanol to hydrocarbons). With InZr/HZSM-5 catalyst, C₅₊ hydrocarbon yield near 20% was obtained at 420 ºC and 50 bar, with a CO_x conversion of 23%, by feeding a CO₂/CO equimolar mixture, and with a H₂/CO_x ratio of 3.