Mantel Capture

Mantel is chasing the part of carbon capture conventional technology can't reach: the hottest industrial processes. Its molten borate salt is a liquid sorbent that stays stable above 600°C, so it captures CO2 directly inside the high-temperature zones of boilers, kilns, and furnaces — exactly where cement, steel, and pulp-and-paper emissions originate and where amine-solvent scrubbers, which need the flue gas cooled first, are inefficient and expensive. The elegance is thermal: because Mantel captures at the source's own heat, it recovers high-grade thermal energy during absorption and reuses it to regenerate the sorbent, which the MIT spinout says cuts capture costs by more than half versus conventional scrubbing while removing roughly 95% of a facility's CO2 without the cooling and large solvent volumes amine systems demand. Halving the cost of capturing the most stubborn industrial emissions would be a genuinely enabling breakthrough for sectors that have no other decarbonization route. The company — founded 2022 out of MIT's chemical engineering department by Cameron Halliday, Danielle Rapson, and Sean Robertson — has moved from lab to field: it raised a $30M Series A (2025) after launching with The Engine, and its first demonstration is under way at Kruger's Wayagamack pulp-and-paper mill in Quebec, designed to capture 2,000 tonnes of CO2 a year, with the company reporting dozens of additional partners across cement, steel, chemicals, power, and data-center infrastructure. If the heat-recovery economics hold at scale, Mantel addresses the hardest-to-abate emissions with the lowest-cost capture in the category.