Capturing and Conversion of Co2 to Methanol in a Chemical Looping Packed Bed System

Some new efforts based on chemical-looping system for capturing and converting CO2 into methanol are discussed in this study. In chemical-looping technology, an oxygen carrier has to be transported between circulating fluidized beds, which require additional energy and processes, like cyclone and seals. This may be one of the main drawbacks at high operating temperatures. In a new reactor concept, the oxygen carrier is not transported but kept inside a packed bed reactor and is alternately exposed to oxidizing and reducing conditions by periodic switching of the feed streams of fuel and air. In a similar operation, it is possible to convert the CO2 to formic acid and hydrogen by using a zero-valent metal (Zn, Al, Fe, Mn)/metal oxide redox cycles under hydrothermal conditions. The oxidized metal can be regenerated by switching the feed stream to a chemical such as glycerin, which is converted to lactic acid: The overall reaction with glycerin is exothermic: Many metals (Cu, Al, Cu+Al, etc.) can react with water to produce H2 efficiently under hydrothermal conditions. The H2 produced by the oxidation of metals could be active to reduce the formic acid into methanol.