CO gas-fermentation CO-PROX CO-SMET CO2 methanation Chemical engineering NiS-NiS2 Technology: general issues acetic acid active phase aluminum alloy foam ammonia borane bio-photolysis bioalcohol biomass conversion catalyst stability ceria chemical hydrogen cobalt coke dark-fermentation electrolysis gasification hydrogen hydrogen energy and fuel cells hydrogen evolution hydrogen production hydrogen purification impurity kinetic models kinetics