Intensified Fluidization Process for Industrial-Scale Coproduction of Value-Added Carbon and CO2-Free H2 from Natural Gas

Commercially, 95% of the hydrogen in US is produced by steam-methane reforming of natural gas. However, SMR converts the carbon to CO_2, and limited by endothermic reaction and energy-intensive pressure-swing H₂ separation. Catalytic decomposition of methane (CDM) has been extensively researched at the laboratory. However, the loss of catalytic reactivity, system pressure buildup, and lacking of CO₂-free external heat supply greatly hurdles the industrial deployment and economic feasibility of CDM process.

Since 2013, our team has strived to develop an innovative modular process for coproducing value-added carbon nanotubes and CO₂-free H₂ by nature gas upgrading. Protected by >3 patents and >10 journal publications, we have successfully integrated auto-thermal pilot-scale chemical looping combustion for CO₂-free heat supply, >95% H₂ purity production, >90% carbon separation efficiency in advanced annular carbon stripper.

In these patented innovations, the Cu-Fe/Al₂O₃ (or Co-Ni/SiO₂-Al₂O₃) was initially reduced exothermally with methane, and reduced oxygen carrier was directly used as catalyst for CDM to produce hydrogen. Depending on chemical composition of catalyst formulation, the tip-growth or base-growth CNTs formed during the methane decomposition was separated by annular separator (patented). In last stage, the reduced catalyst, after CNT harvesting, was exothermally regenerated by air, and recirculated back to reducer for next reaction cycle. Taking advantage of auto-thermal chemical looping operation, this process enables CO₂-free heat supply for endothermic methane decomposition. The same CuO-Fe₂O₃ material functioned as oxygen carrier for chemical looping and as a catalyst for methane decomposition. Unique annular configuration in fluidization separator greatly improve carbon separation with lower solid feed rates. The preliminary TEA suggested significant improvement in energy efficiency (45% savings on electricity), and greater than 50% capital cost reduction compared with state-of-the-art technologies for H₂ production due to elimination of a number of unit operations: WGS, PSA and CO₂ capture units, which seamlessly aligned with RAPID’s missions.