Comparison Of Aminothermal And Hydrothermal Synthesis Of SAPO-34: Impact Of Synthesis Conditions On Catalyst Characteristics And MTO Catalytic Performance

Abstract

Abstract The present study investigates the aminothermal synthesis of SAPO-34 using various templates, including morpholine, diethylamine, triethylamine, triethanolamine, diglycolamine, and diisopropylamine, under static conditions. The catalyst's characteristics were assessed through XRD, SEM, and EDS analyses, and the catalytic behavior of the samples was studied in the MTO reaction. The results indicate that only morpholine leads to the formation of pure SAPO-34, and it is essential to regulate the crystallization time to prevent the formation of SAPO-20. Furthermore, the impact of the order of reactant addition and the intensity of stirring during aging on catalyst characteristics was investigated, and the outcomes were compared to those of the hydrothermally synthesized sample. The findings reveal that the aminothermal method reduces the crystallization time and enhances silica incorporation. However, this technique is recommended for the synthesis using polar templates or in the presence of polar additives. The utilization of non-polar templates such as DEA and TEA resulted in very thick pastes. The catalytic performance of the aminothermal samples was comparable to that of the hydrothermal samples, with a methanol conversion of over 98% and a selectivity to light olefins of approximately 80%. Nevertheless, the impact of preparation, aging, and post-treatment conditions on the hydrogen transfer index and alkanes production was significant.