A method of catalytic ammonia decomposition is provided. The method includes: flowing ammonia into a reactor charged with a medium entropy metal alloy (MEA) catalyst including a first principal metal, a second principal metal, and a third principal metal, where each of the principal metals is independently selected without repetition from the group consisting of Co, Cr, Fe, Mn, Ni, Al, Cu, Zn, Ti, Zr, Mo, V, Ru, Rh, Pd, Ag, W, Re, Ir, Pt, Au, Ce, Y, Yb, Sn, Ga, In, and Be; and catalytically decomposing the ammonia into hydrogen and nitrogen over the MEA catalyst in the reactor at a reaction temperature between 200 C. and 900 C.

The presently disclosed embodiments relate to the utilization of coal-derived fine mineral matter in chemical recycling of plastics or of solid mixed plastic waste. The instantly disclosed mineral based catalyst benefits the processes of catalytic cracking, gasification and steam reforming to maximize carbon utilization and production of plastics of original quality from recycled or renewable feedstocks while reducing the plastic pollution in the environment. The catalyst can be based on inorganic fine mineral matter, a natural ancient mineral mixture found in coal deposits and containing a plurality of transition metals, such as iron, copper, and manganese, as well as calcium, barium, magnesium, potassium, sodium, which can act as co-catalysts. Addition of the catalyst can convert plastic to syngas at a faction of the energy of conventional technologies.