Silicoaluminophosphate SAPO-34 zeotypes have been hydrothermally synthesized by using a tailor-designed zwitterionic amino acid of 3-hydroxy-4-triethylaminobutyric acid (Et-LC). The unnatural zwitterionic amino acid possessing both triethyl ammonium cationic moiety and anionic carboxylate group promoted SAPO-34 crystallization, allowed to decrease acidity of the as-obtained SAPO-34 catalysts, and slightly generated mesopores without affecting the microporosity. While natural amino acids either induced polymorphism due to the amino or ammonium moiety incommensurate with the chabazite unit, or showed inability to create mesopores because of the non-deprotonated carboxylic group, thus failing to meet the stringent SAPO-34 synthetic requirements of neutral pH, high temperature and appropriate templates. The Et-LC mediated SAPO-34 crystals were demonstrated to be much more effective in catalyzing the methanol to olefin (MTO) reactions with lifetime improved to 533 min, the ethylene plus propylene selectivity preserved at 81%, and coke content decreased to 8%, in comparison to those of the conventional microporous SAPO-34 zeolite of 389 min, 81%, and 17.5%.

硅铝磷酸盐SAPO-34分子型已经通过使用专门设计的3-羟基-4-三乙基氨基丁酸（Et-LC）的两性离子氨基酸水热合成。同时具有三乙基铵阳离子部分和阴离子羧酸盐基团的非天然两性离子氨基酸可促进SAPO-34结晶，降低所获得的SAPO-34催化剂的酸度，并在不影响微孔率的情况下稍微产生中孔。虽然天然氨基酸由于菱沸石单元的氨基或铵部分而引起多态性，或者由于未去质子化的羧基而显示无法形成中孔，因此不能满足中性pH的严格SAPO-34合成要求，高温和合适的模板。