Hydrogen plays a key role in many industrial applications and is currently seen as one of the most promising energy vectors. Many efforts are being made to produce hydrogen with zero CO2 footprint via water electrolysis powered by renewable energies. Nevertheless, the use of fossil fuels is essential in the short term. The conventional coal gasification and steam methane reforming processes for hydrogen production are undesirable due to the huge CO2 emissions. A cleaner technology based on natural gas that has received special attention in recent years is methane pyrolysis. The thermal decomposition of methane gives rise to hydrogen and solid carbon, and thus, the release of greenhouse gases is prevented. Therefore, methane pyrolysis is a CO2-free technology that can serve as a bridge from fossil fuels to renewable energies.

The Carbon2Chem® project aims to convert exhaust gases from the steel industry into chemicals such as methanol to reduce CO2 emissions. Here, H2 is required for the conversion of CO2 into methanol. Although much effort is put to produce H2 from renewables, the use of fossil fuels, especially natural gas, seems to be fundamental in the short term. For this reason, the development of clean technologies for the processing of natural gas with a low environmental impact has become a topic of utmost importance. In this context, methane pyrolysis has received special attention to produce CO2‐free H2.

Wheat bran is a lignocellulosic waste of milling industry. It contains hemicelluloses which can be valorized into arabitol and xylitol via a few-step approach. It begins with extraction and hydrolysis of hemicelluloses to produce a solution of xylose and arabinose along with proteins and inorganic salts. This work focusses on the purification of sugars of this hydrolysate and the subsequent catalytic production of sugar alcohols. A purification process based on the recovery of sugars by anionic extraction with a boronic acid, followed by back-extraction and a further refining step with ion exchange resins is described. After this process, a high purity sugars solution (~90%) free of inorganic elements and proteins was obtained. The feasibility of the process was also highlighted by a successful recycling of the organic phase containing the boronic acid. The hydrogenation of purified sugars was then performed over Ru/H-ZSM-5. A high yield into pentitols of ~70% with 100% selectivity was achieved. Importantly, the catalytic hydrogenation of sugars in the hydrolysate prior to purification did not occur. We determined that proteins caused the deactivation of the catalyst and consequently the inhibition of the production of sugar alcohols.

This article considers catalytic isomerization of aldo-pentoses into keto-pentoses combined with product recovery by anionic extraction.

The extraction/hydrolysis process of arabinoxylans from destarched wheat bran was studied in this work using different mesoporous silica supports and the corresponding RuCl3-based catalysts. The effects of temperature, time, catalyst supports and ruthenium catalysts were investigated and discussed in terms of the arabinoxylans extraction yield and their polymerization degree. Relatively high temperatures (180 ºC), short extraction times (10 minutes) and RuCl3 supported on Al-MCM-48 led to a high amount of arabinoxylans extracted (78%) with a low molecular weight (9 KDa). Finally, a relation between the operating conditions, the arabinoxylans extraction yield and the molecular weight was stablished based on the obtained results. Abbreviation: AXs, arabinoxylans; DWB, destarched wheat branKeywords: Hemicelluloses fractionation, wheat bran, arabinoxylans, heterogeneous catalysis, hydrothermal process, biomass Chemical compounds studied in this articleXylose (PubChem CID: 135191); Arabinose (PubChem CID: 439195) Highlights:-Effects of ruthenium catalyst, temperature, time and catalyst support are discussed -RuCl3-based catalysts show good activity for the arabinoxylans extraction from wheat bran -Liquid extracts are characterized in terms of sugars, molecular weight and purity

This review article deals with the challenge to identify catalyst materials from literature studies for the ammonia decomposition reaction with potential for application in large-scale industrial processes. On the one hand, the requirements on the catalyst are quite demanding. Of central importance are the conditions for the primary reaction that have to be met by the catalyst. Likewise, the catalytic performance, i.e., an ideally quantitative conversion, and a high lifetime are critical as well as the consideration of requirements on the product properties in terms of pressure or by-products for potential follow-up processes, in this case synthesis gas applications. On the other hand, the evaluation of the multitude of literature studies poses difficulties due to significant varieties in catalytic testing protocols.

9The hydrolysis process of real a fraction of arabinoxylans derived from wheat bran was studied 10 using different mesoporous silica materials and the corresponding RuCl3 catalysts in water. The 21-RuCl3/Al-MCM-48 accelerates conversion of arabinoxylans into arabinose and xylose. 22-RuCl3/Al-MCM-48 catalysts inhibit further dehydration into furfural. 23-Significant reduction in hydrolysis time from several hours to 15 min is achieved. 24-A two-step process using RuCl3/Al-MCM-48 maximizes C5 sugars from wheat bran. 252

No abstract