2024 AIChE Annual Meeting
(236c) Scaling up Medium-Temperature Reverse Water-Gas Shift Catalysis
Author
Matthew Kanan - Presenter, Stanford University
Reverse water-gas shift (RWGS) provides a critical link between established water electrolysis and syngas-to-liquids technologies to enable integrated power-to-liquids (PtL) production. Current (pre)commercial RWGS technologies utilize Ni catalysts that are derivatives of steam reforming catalysts. These materials catalyze not just RWGS but also methane (CH4) and coke formation. To suppress methane and avoid coking, conventional Ni RWGS catalysts must be operated at very high temperatures (typically 900-1100 °C) where RWGS is thermodynamically favored over these competing reactions. This temperature regime necessitates expensive materials of construction and complicates heat integration with the rest of a PtL process. We have developed RWGS catalysts that are composed only of alkali carbonates (e.g. K2CO3) dispersed in mesoporous supports such as Al2O3 (“dispersed carbonate RWGS catalysts). Because they have no transition metals, dispersed carbonate catalysts are extremely selective for RWGS, enabling operation in a medium-temperature regime without CH4 or coke formation. In independent testing, high activity and essentially 100% selectivity for CO has been achieved at industrially relevant gas hourly space velocity (>10,000 h–1) at ≥500 °C with no degradation of performance observed over multiple weeks. The ease with which dispersed carbonates can be synthesized enables ultra-low-cost manufacturing using existing supply chains and production facilities. This talk will describe the development, state-of-the-art, and scale-up of dispersed carbonate RWGS catalysis and their application in sustainable chemical and fuel synthesis.