Solid-state microwave assisted batch and flow synthesis, and life cycle assessment, of titanium containing UVM-7 mesoporous silica

Abstract

UVM-7 is a bimodal mesoporous silica material that can be prepared in a short time with microwave assisted synthesis (MAS). It is prepared following the atrane route, that allows the synthesis of mixed silicas including other elements with homogeneous distribution. We report herein the preparation of Ti-UVM-7 with using the atrane route in combination with MAS with solid-state generators. The synthesis has been optimized and scaled-up in batch. Also, the flow synthesis has been developed. These materials have not been prepared before using solid-state generators, nor microwave-assisted flow chemistry. The materials have been characterized by XRD, N₂ adsorption-desorption, TEM, EDX, Raman, and Z potential. The materials can be prepared in less than 10 min with a Si/Ti ratio of up to 3.8, and a homogeneous Ti distribution within the UVM-7 silica structure. Scaled-up synthesis produces 33 g of Ti-UVM-7 in 10 min and 12 g h⁻¹ in batch and flow synthesis respectively. The optical properties and sun protection factor of the resulting materials were studied. The band gap decreases as titanium concentration increases, reaching 4.1 eV for the highest concentration. Life Cycle Assessment confirms a strong reduction in the impact derived from the scale-up with similar values of approximately 10 points in the single score for the preparation of 1 kg of Ti-UVM-7.