Method for synthesizing lactide by catalyzing lactic acid with Sn-MCM-41 through one-step gas phase method

The invention relates to a method for synthesizing lactide by using Sn-MCM-41 to catalyze lactic acid through a one-step gas phase method, which comprises the following steps: (1) grinding a catalyst Sn-MCM-41, and loading in a fixed bed reactor of a fixed bed reaction device; and (2) respectively and simultaneously introducing lactic acid and nitrogen into the fixed bed reactor, heating and reacting to obtain a lactide crude product, cooling and collecting. The catalyst Sn-MCM-41 used in the invention has high activity and high selectivity, realizes high conversion rate of L-LA and high selectivity of L-LT under a gas phase condition, avoids use of toxic solvents, is green and environment-friendly, and has potential industrial prospects due to continuous reaction devices. 本发明涉及一种Sn-MCM-41催化乳酸一步气相法合成丙交酯的方法，包括如下步骤：(1)将催化剂Sn-MCM-41研磨，搭载于固定床反应装置的固定床反应器中；(2)将乳酸和氮气分别同时通入固定床反应器中，加热反应，得到丙交酯粗产物，冷却，收集。本发明所使用的催化剂Sn-MCM-41具有高活性和高选择性，在气相条件下，实现了L-LA的高转化率和L-LT的高选择性，同时避免有毒溶剂的使用，绿色环保，且反应装置的连续化，具有潜在的工业化前景。