Natural gas pyrolysis in a molten salt reactor

RODRIGUEZ REARTES, SABRINA BELÉN; LLOVELL, FÈLIX

Barcelona, España

Congreso; 15th Mediterranean Congress of Chemical Engineering (MeCCE-15); 2023

IQS

Renewable energy sources are being implemented worldwide as one of the measures to mitigate climate change. Hydrogen appears as one of the most promising future energy sources, but its production processes need to be low in CO2 emissions, thus the so called green and blue hydrogen can accomplish the desired standards. The first one is obtained from water electrolysis using renewable electricity, whereas the second one comes from fossil fuels with carbon capture and storage (CCS). Other types of hydrogen production processes are also being considered. In particular, natural gas pyrolysis which leads to hydrogen and pure carbon can have a great potential [1]. The cracking of natural gas within a liquid bath of molten salt or metal is a process being considered, but very few works are devoted to this technology. On it, the pure solid carbon float and can be recovered from the liquid bath whereas the gaseous stream leaves the reactor for its further purification. Moreover, high-purity solid carbon can be sold as a valuable subproduct. This is a key point to improve the process economics and enhance its market competitiveness. In this work we perform the techno-economic assessment for a hydrogen production process based on a molten salt pyrolysis reactor. A molten salt mixture of MnCl2 and KCl [2] due to its synergy to catalyse the reaction and the high methane conversions observed in the literature. A medium size plant for a hydrogen production capacity of 0.75 kg/s is considered. A simplified flow diagram of the process is presented in Fig. 1. Briefly, the natural gas is cracked in a pyrolysis reactor from which a pure solid carbon is recovered. Moreover, a gas outlet is obtained and treated to get hydrogen under the required specification and off-gas which is split, recycling part of it to the reactor to enhance H2 and C production, whereas the other part is combusted to prevent residual compounds (as nitrogen) accumulation. Special attention will be paid to the We will also evaluate the possibility to purify the outlet reactor stream to fulfil the requirements of other chemical-added products, e.g., methanol.The process model is developed in ASPEN Plus V12.