Evolution paths from gray to turquoise hydrogen via catalytic steam methane reforming: Current challenges and future developments

Fossil fuel depletion, global warming, climate change, and steep hikes in the price of fuel are driving scientists to investigate commercial and environmentally friendly energy carriers like hydrogen. Steam methane reforming (SMR), a current commercial route for H-2 production, has been considered the best remedy to fulfill the requirements. Despite the remarkable quantity of H-2 produced by the SMR, this technology still faces major challenges such as catalyst deactivation due to the sintering of metal nanoparticles, coking, and generation of a large quantity of CO2. Firstly, the effects of catalyst types, kinetic models, and operating conditions on high-yield H-2 production, the evolution path from gray to blue, via the conventional SMR are comprehensively reviewed. Secondly, exploiting intensified techniques such as membrane technology, sorption, fluidization, and chemical looping for SMR to blue H-2 are discussed in detail. Further, a novel and sustainable path for the SMR process, hybridizing the use of novel materials and emerging technologies to produce turquoise H-2, is proposed. Finally, the critical points for steam reforming process technology that can help leverage environmental, social, and governance (ESG) profiling have been discussed.