No abstract

Controlled continuous crystallization of the active pharmaceutical ingredient (API) telmisartan (TEL) has been conducted from TEL/DMSO solutions by antisolvent crystallization in deionized water using membrane micromixing contactors. The purpose of this work was to test stainless-steel membranes with ordered 10 μm pores spaced at 200 μm in a stirred-cell (batch, LDC-1) and crossflow (continuous, AXF-1) system for TEL formation. By controlling the feed flow rate of the API and solvent, through the membrane pores as well as the antisolvent flow, it was possible to tightly control the micromixing and with that to control the crystal nucleation and growth. Batch crystallization without the membrane resulted in an inhomogeneous crystallization process, giving a mixture of crystalline and amorphous TEL materials. The rate of crystallization was controlled with a higher DMSO content (4:1 DMSO/DI water), resulting in slower crystallization of the TEL material. Both membrane setups, stirred batch and the crossflow, yielded the amorphous TEL particles when deionized water was used, while a crystalline material was produced when a mixture of DI water and DMSO was used.

No abstract

Utilisation of CO2 as a chemical reagent is challenging, due to the molecule's inherent chemical stability. However, CO2 reacts promptly at high temperature (∼1000 °C) with alkaline‐earth oxides to form carbonates and such reactions are used towards capture and re‐utilisation. In this work, this concept is extended and CO2 is utilised as a reagent to modify the crystal structure of mixed‐metal inorganic solids. Modification of the crystal structure is a “tool” used by materials scientists to tailor the physical property of solids. CO2 gas was reacted with several isostructural mixed‐metal oxides Sr2CuO3, Sr1.8Ba0.2CuO3 and Ba2PdO3. These oxides are carefully selected to show anion vacancies in their crystal structure, to act as host sites for CO2 molecules, leading to the formation of carbonate anions, (CO3)2−. The corresponding oxide carbonates were formed successfully and the favourable formation of SrCO3 as secondary phase was minimised via an innovative, yet simple synthetic procedure involving alternating of CO2 and air. We also derived a simple model to predict the kinetics of the reactions for the cuprates, using first‐principles density functional theory and assimilating the reaction to a gas‐surface process.