Production of silica aerogel microparticles loaded with ammonia borane by batch and semicontinuous supercritical drying techniques

Research Progress on Modification of Aerogels by Chemical Vapor Deposition

Aerogels are three-dimensional nanomaterials with low thermal conductivity, low density, high specific surface area, and high porosity. They have demonstrated remarkable performance advantages in thermal insulation, catalysis, and adsorption in recent years. However, their inherent brittleness and weak skeletal structure limit their applications. In order to improve the resilience and expand the capabilities of aerogels, it is essential to optimize their intrinsic properties. The chemical vapor deposition (CVD) method offers a number of advantages, including fine control, high selectivity, and the ability to modify the aerogel in both the outer surface and the inner layer. This approach allows for reinforcement of the gel skeleton while achieving functionalization. This paper reviews the research progress of aerogel modification by the CVD method with a focus on hydrophobic modification, structural improvement, antioxidant modification, catalytic modification, etc. In light of the current demand for aerogel applications and the difficulties encountered in modifying aerogels, this review proposes future research directions for aerogel modification by CVD.

Experimental Investigation and CFD Modeling of Supercritical Adsorption Process

The kinetics of the supercritical adsorption process was experimentally studied by the example of ”ibuprofen-silica aerogel” composition obtainment at various parameters: Pressure 120–200 bar and temperature 40–60 °C. Computational Fluid Dynamics (CFD) model of the supercritical adsorption process in a high-pressure apparatus based on the provisions of continuum mechanics is proposed. Using supercritical adsorption process kinetics experimental data, the dependences of the effective diffusion coefficient of active substance in the aerogel, and the maximum amount of the adsorbed active substance into the aerogel on temperature and pressure are revealed. Adequacy of the proposed model is confirmed. The proposed mathematical model allows predicting the behavior of system (fields of velocity, temperature, pressure, composition, density, etc.) at each point of the studied medium. It makes possible to predict mass transport rate of the active substance inside the porous body depending on the geometry of the apparatus, structure of flow, temperature, and pressure.

Ammonia Borane: An Extensively Studied, Though Not Yet Implemented, Hydrogen Carrier

Ammonia borane H3N−BH3 (AB) was re-discovered, in the 2000s, to play an important role in the developing hydrogen economy, but it has seemingly failed; at best it has lagged behind. The present review aims at analyzing, in the context of more than 300 articles, the reasons why AB gives a sense that it has failed as an anodic fuel, a liquid-state hydrogen carrier and a solid hydrogen carrier. The key issues AB faces and the key challenges ahead it has to address (i.e., those hindering its technological deployment) have been identified and itemized. The reality is that preventable errors have been made. First, some critical issues have been underestimated and thereby understudied, whereas others have been disproportionally considered. Second, the potential of AB has been overestimated, and there has been an undoubted lack of realistic and practical vision of it. Third, the competition in the field is severe, with more promising and cheaper hydrides in front of AB. Fourth, AB has been confined to lab benches, and consequently its technological readiness level has remained low. This is discussed in detail herein.

Process intensification in chemical engineering: general trends and Russian contribution

Minimization of the costs with simultaneous increase in the raw materials and energy use efficiency is a challenge for the modern world. One of the most effective tools to solve this task is the use of process intensification (PI), first proposed by Ramshaw C. The incentive for process intensification, Proceedings, 1st Intl. Conf. Proc. Intensif. for Chem. Ind., 18, BHR Group, London, 1995, p. 1. and then extended by Stankiewicz AI, Moulijn JA. Process intensification: transforming chemical engineering. Chem Eng Prog 2000: 22–34. In the presented review, some principles of PI in chemical engineering and their application for wide variety of processes is discussed. The role of the Russian scientist with a research background is carried out in other countries.