Polyethylene Glycol Enfolded KBr Assisted Base Catalyzed Synthesis of Dimethyl Carbonate from Methanol and Carbon Dioxide

TiO2-Doped CeO2 Nanorod Catalyst for Direct Conversion of CO2 and CH3OH to Dimethyl Carbonate: Catalytic Performance and Kinetic Study

A new class of TiO₂-doped CeO₂ nanorods was synthesized via a modified hydrothermal method, and these nanorods were first used as catalysts for the direct synthesis of dimethyl carbonate (DMC) from CO₂ and CH₃OH in a fixed-bed reactor. The micromorphologies and physical-chemical properties of nanorods were characterized by transmission electron microscopy, X-ray diffraction, N₂ adsorption, inductively coupled plasma atomic emission spectrometry, X-ray photoelectron spectroscopy, and temperature-programmed desorption of ammonia and carbon dioxide (NH₃-TPD and CO₂-TPD). The effects of the TiO₂ doping ratio on the catalytic performances were fully investigated. By doping TiO₂, the surface acid-base sites of CeO₂ nanorods can be obviously promoted and the catalytic activity can be raised evidently. Ti_0.04Ce_0.96O₂ nanorod catalysts exhibited remarkably high activity with a methanol conversion of 5.38% with DMC selectivity of 83.1%. Furthermore, kinetic and mechanistic investigations based on the initial rate method were conducted. Over the Ti_0.04Ce_0.96O₂ nanorod catalyst, the apparent activation energy of the reaction was 46.3 kJ/mol. The reaction rate law was determined to be of positive first-order to the CO₂ concentration and the catalyst loading amount. These results were practically identical with the prediction of the Langmuir-Hinshelwood mechanism in which the steps of CO₂ adsorption and activation are considered as rate-determining steps.

Direct Synthesis of Dimethyl Carbonate from Carbon Dioxide and Methanol at Room Temperature Using Imidazolium Hydrogen Carbonate Ionic Liquid as a Recyclable Catalyst and Dehydrant

The direct synthesis of dimethyl carbonate (DMC) from CO₂ and CH₃ OH was achieved at room temperature with 74 % CH₃ OH conversion in the presence of an imidazolium hydrogen carbonate ionic liquid ([C_n C_m Im][HCO₃ ]). Experimental and theoretical results reveal that [C_n C_m Im][HCO₃ ] can transform quickly into a CO₂ adduct, which serves as an effective catalyst and dehydrant. Its dehydration ability is reversible. The energy barrier of the rate-determining step for the DMC synthesis is only 21.7 kcal mol^-1 . The ionic liquid can be reused easily without a significant loss of its catalytic and dehydrating ability.

Fixation of carbon dioxide into dimethyl carbonate over titanium-based zeolitic thiophene-benzimidazolate framework

A titanium-based zeolitic thiophene-benzimidazolate framework has been designed for the direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide. The developed catalyst activates carbon dioxide and delivers over 16% yield of DMC without the use of any dehydrating agent or requirement for azeotropic distillation.

Dimethyl carbonate synthesis from carbon dioxide using ceria–zirconia catalysts prepared using a templating method: characterization, parametric optimization and chemical equilibrium modeling

In this paper, a series of Ce_xZr_1−xO₂ solid solution spheres were synthesized by exo- and endo-templating methods and tested for dimethyl carbonate (DMC) synthesis using direct conversion of CO₂.