Urea methanolysis is a green alternative to synthesize dimethyl carbonate (UM-to-DMC). However, it is strongly challenged by the generated NH₃ induced thermodynamic equilibrium limitation and the azeotropic products’ separation. Herein, these predicaments are well-relieved by introducing membranes in both reaction and product separation. An NH₃ permselective membrane reactor (MR) based on modified SAPO-34 membrane is successfully realized for UM-to-DMC. The permselectivity and acidity of the SAPO-34 membrane are significantly adjusted to cater the strict molecular sieving of NH₃/methanol and chemical inertness upon the reaction. The MR exhibits excellent reactant conversion and DMC selectivity, resulting in >139% higher DMC yield than that of the nonmembrane reactor, due to in situ removal of NH₃ by the membrane. The MR also demonstrates reliable chemical, thermal, and mechanical stability during >2000 h. Moreover, the regular SAPO-34 membrane with controlled thickness presents remarkable separation performance for the methanol–DMC azeotrope, in which the methanol–DMC separation factors and the methanol permeance are 1–2 orders of magnitude higher than those of the polymeric membranes. This study suggests the great potential that integration of such membranes offers for process intensification, energy savings, and efficiency improvement in a series of urea alcoholysis and even other NH₃ releasing reactions.

中文翻译：

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双孔膜在尿素醇解中作为NH ₃选择性渗透反应器和恒沸分离器

尿素甲醇分解法是合成碳酸二甲酯（UM-to-DMC）的绿色替代品。然而，它受到产生的NH ₃引起的热力学平衡极限和共沸产物分离的强烈挑战。在本文中，通过在反应和产物分离中引入膜很好地消除了这些困境。基于改进的SAPO-34膜的NH ₃选择性渗透膜反应器（MR）已成功实现用于UM-to-DMC。可以对SAPO-34膜的渗透选择性和酸度进行显着调整，以满足严格的NH ₃分子筛/甲醇和反应中的化学惰性。MR表现出出色的反应物转化率和DMC选择性，由于原位去除NH ₃，其DMC收率比非膜反应器高139％以上。通过膜。MR还证明了在> 2000小时内的可靠化学，热和机械稳定性。此外，具有受控厚度的常规SAPO-34膜对甲醇-DMC共沸物具有出色的分离性能，其中甲醇-DMC分离因子和甲醇渗透率比聚合物膜高1-2个数量级。这项研究表明，在一系列尿素醇解甚至其他释放NH _3的反应中，这种膜的集成具有提高工艺强度，节约能源和提高效率的巨大潜力。