A note on the acid strength of porous materials assessed by thermal methods

Abstract Mesoporous materials containing acid sites are special type of heterogeneous catalysts, having bigger pores than zeolites have. These materials can be (and some of them are) used as catalysts for refining and petrochemical applications, as well as in emerging technologies such as biomass conversion. Therefore, there is interest in studying these materials from many perspectives. Here, an evaluative appraisal about a characterisation tool that is sometimes used for characterising the acid strength of these catalysts is presented; ammine temperature programmed desorption. It can sometimes get confused with NH3 temperature programmed desorption but the principles, and limitations, are different. The current understanding of this technique is discussed. The discussion is based on propyl-ammine as probe molecule, but it is applicable to any gaseous alkylamine used as molecular probe for this assessment.