Electrified non-thermal plasma (NTP) catalytic hydrogenation is the promising alternative to the thermal counterparts, being able to be operated under mild conditions and compatible with green electricity/hydrogen. Rational design of the catalysts for such NTP-catalytic systems is one of the keys to improve the process efficiency. Here, we present the development of siliceous mesocellular foam (MCF) supported Cu catalysts for NTP-catalytic CO2 hydrogenation to methanol. The findings show that the pristine MCF support with high specific surface area and large mesopore of 784 m2·g−1 and ~8.5 nm could promote the plasma discharging and the diffusion of species through its framework, outperforming other control porous materials (viz., silicalite-1, SiO2, and SBA-15). Compared to the NTP system employing the bare MCF, the inclusion of Cu and Zn in MCF (i.e., Cu1Zn1/MCF) promoted the methanol formation of the NTP-catalytic system with a higher space-time yield of methanol at ~275 μmol·gcat−1·h−1 and a lower energy consumption of 26.4 kJ·
Methane cracking is considered a bridge technology between gray and green hydrogen production processes. In this work an experimental study of methane cracking in molten tin is performed. The tests were conducted in a quartz reactor (i.d. = 1.5 cm, L = 20 cm) with capillary injection, varying temperature (950–1070 °C), inlet methane flow rate (30–60 mL·min–1) and tin height (0–20 cm). The influence of the residence time in the tin and in the headspace on methane conversion and on carbon morphology was investigated. The conversions obtained in tin and in the empty reactor were measured and compared with results of detailed kinetic simulations (CRECK). Furthermore, an expression of a global kinetic constant for methane conversion in tin was also derived. The highest conversion (65% at Q0 = 30 mL·min–1 and t = 1070 °C) is obtained for homogeneous gas phase reaction due to the long residence time (70 s), the presence of tin leads to a sharp decrease of residence time (1 s), obtaining a conversion of 35% at 1070 °C, thus meaning that tin owns a role in the reaction. Carbon characterization (scanning electron microscopy, Raman) reported a change in carbon toward sheet-like structures and an increase of the carbon structural order in the presence of molten tin media.
