Dual-Role Membrane as NH₃ Permselective Reactor and Azeotrope Separator in Urea Alcoholysis

Abstract

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.

Reactive Extraction Enhanced by Synergic Microwave Heating: Furfural Yield Boost in Biphasic Systems

“…In conclusion, we report a consistent yield improvement of approximately 10–15 mol % in the dehydration of xylose by synergistically combining two different factors: microwave heating and reactive extraction using two phases with asymmetric polarity and volumes. Generally, the improvement of the yield of a chemical process is obtained by the development and optimization of a catalyst, possibly assisted by plasmonics or ultrasound, or by varying the solvent system and using membranes or other components for the in situ separation of the various products . In this study, we show how a more optimal section of the reaction parameter space can be reached by the combination of microwave heating and specific biphasic conditions and by varying the dielectric properties of both phases.…”

“…Generally,t he improvement of the yield of ac hemical process is obtainedb yt he development and optimization of ac atalyst, possibly assisted by plasmonicso ru ltrasound, or by varying the solvents ystem and using membranes or other components for the in situ separation of the various products. [31][32][33][34][35][36][37] In this study,w es how how a more optimal sectiono ft he reactionp arameter space can be reachedb ythe combination of microwave heatinga nd specific biphasic conditions and by varying the dielectric properties of both phases. Such forms of synergism can become an important tool for organic synthesis and chemical processes.…”

Zinc-based Ultrasensitive Microscopic Barrier Assay (ZnUMBA): a live-imaging method for detecting epithelial barrier breaches with spatiotemporal precision

“…Other fluorogenic dyes that increase significantly in fluorescence upon binding their target could be used instead of FZ3. For example, fluorogenic dyes that are ligands for self-labeling tags such as Halo tags (Zeng et al, 2019) would be a good option. In this case, the fluorogenic Halo dye would be added to the apical side of the epithelium, and a Halo-tagged basolateral transmembrane protein would be expressed in the cells, or recombinant Halo-tagged protein would be added to the basal side.…”

Interfacial Ions Sieving for Ultrafast and Complete Desalination through 2D Nanochannel Defined Graphene Composite Membranes

“…The desalination performance of fGraphene membranes was measured by VMD at 40–80 °C. The saline solution was introduced into the lumen side of the membrane module with a flow rate of 2 mL min –1 by a constant pump . The retentate side of the membrane module was connected in sequence with the sample collector, which is immersed in a liquid nitrogen cold trap, and the vacuum pump, by which the pressure of the retentate side was kept around 100 Pa.…”