Temperature-induced reduction of methanol synthesis catalysts

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Copper-based methanol catalysts exhibit good low-temperature activity and high selectivity, and are typically used in low to medium pressure processes. Main components: CuO accounts for 35%–45% and is the active ingredient; ZnO accounts for 35%–45% and Al2O3 accounts for 5%, and these serve as co-catalysts. Among them, ZnO forms the framework of the catalyst and plays a role in stabilizing and protecting the copper crystals. Copper-based catalysts are prone to poisoning; sulfides, chlorine, oils, NH3, phosphorus, arsenic, and the like can all poison the catalyst and render it inactive. When the sulfur absorption level of the catalyst reaches 3.5% on average, its activity is essentially lost. Catalyst reduction is divided into two types: high-H2 reduction and low-H2 reduction. In the case of low-H2 reduction, the bed temperature is easy to control; the catalyst retains high activity after reduction, but the reduction time is long. High H2 reduction: Strict control of the bed temperature is employed, with the water output serving as an indicator to regulate the progress of the reduction process. The advantage of this method is short reduction time ； It usually takes about 40 hours. Shortcomings: The operation requires great care and precision; any carelessness can lead to severe overheating of the catalyst bed, resulting in catalyst deactivation and rendering it unusable. Reduction principle: CuO + H2 = Cu + H2O + 86.7 KJ/mol; it is a highly exothermic reaction. ZnO and Al2O3 are not reduced due to the high metallic reactivity of Zn and Al.