Synthesis of SAPO-34 with the presence of additives and their catalytic performance in the transformation of chloromethane to olefins

Abstract

SAPO-34 molecular sieves were synthesized in the presence of soluble starch, sodium dodecyl sulfate and cetyltrimethylammonium bromide as the additives under hydrothermal conditions, and the differences stemmed from the additives among all obtained SAPO-34 samples were characterized by XRD, SEM, BET, NH 3 -TPD and TG. Compared with the conventional SAPO-34 sample, the SAPO-34 samples modified by sodium dodecyl sulfate and cetyltrimethylammonium bromide showed less crystalline order, enlarged mesopore volume and external surface area and a reduction in total acidity amounts. Meanwhile, the SAPO-34 modified by soluble starch exhibited more total acidity amounts than the conventional SAPO-34 samples. The SAPO-34 samples modified by sodium dodecyl sulfate and cetyltrimethylammonium bromide showed better catalytic stability and less carbon deposition than the conventional SAPO-34 catalyst in the conversion of chloromethane to olefins due to the reduction in total acid sites and the increasing mesopore volume. The overall results of this study demonstrate that it is an effective way to modify the SAPO-34 molecular sieve with sodium dodecyl sulfate and cetyltrimethylammonium bromide as the additives for improving the SAPO-34 catalyst stability in the transformation of chloromethane to olefins.Keywosrds SAPO-34 Á Soluble starch Á Sodium dodecyl sulfate Á Cetyltrimethylammonium bromide Á Chloromethane Á Light olefins Electronic supplementary material The online version of this article (

Understanding Hydrodechlorination of Chloromethanes. Past and Future of the Technology

“…In recent years, the use of chloromethanes for the production of olefins has become an attractive alternative route. MCM has been widely employed as an intermediate in a two-step method to produce olefins from methane (Scheme 4) , usually employing zeolytic catalysts with chabazite-type structure (silicoaluminophosphates (SAPO) [209][210][211][212][213][214][215][216][217][218][219][220][221] and zeolite socony mobils (ZSM) [220][221][222][223][224][225][226][227][228][229][230]).…”

Enhanced selectivity to olefins in the hydrodechlorination of trichloromethane using Ag-Pd on activated carbon catalysts

“…While the direct production of olefins can be of higher interest [13][14][15], most studies available obtain methane as the main reaction product of the HDC of chloromethanes. Recently, good results were reported for the dechlorination of monochloromethane in terms of selectivity to ethylene, propylene and butylene, using zeolite catalysts [16][17][18][19].…”