A system (100, 222, 300, 1200) for decarbonizing gases using adiabatic calcium looping, pressure swing and a pair of fixed bed, alternating, pressurized reactors (102, 104, 306, 308), the system comprising: a) an input gas manifold comprising a plurality of valves (108, 110) and having at least one input that receives syngas (112, 328, 1806) and steam (114, 328, 1806); b) a pair of pressure vessels comprising a first and second pressure vessel (102, 104, 306, 308, 1202, 1708, 1708', 1802, 1804), each of the first and second pressure vessel comprising: i. a fixed bed of sorbent (106, 1100, 1204, 1712); ii. an input that is coupled to an output of the input gas manifold; and iii. an output; c) an output gas manifold comprising a plurality of valves (122, 124) and having a first input that is coupled to the output of the first pressure vessel (102, 306, 1202, 1708, 1802) and a second input that is coupled to the output of the second pressure vessel (104, 308, 1804); d) a valve controller having at least one output that is coupled to the input gas manifold and at least one output that is coupled to the output gas manifold; and e) a compressor (120, 304, 1704) comprising an input port coupled to a port of the output gas manifold, the compressor being arranged to provide enough vacuum to the output gas manifold such that when the first or second pressure vessel exhausts CO 2 their partial pressure is below a decomposition line for calcium carbonate; characterised in that: the fixed bed of sorbent (106, 1100, 1204, 1712) comprises a lime, limestone honeycomb monolith comprising calcium aluminate and dolomite as additives that reduce the reaction time by increasing permeability of the fixed bed sorbent at high temperature; the pair of pressure vessels (102, 104, 306, 308, 1202, 1708, 1708' 1802, 1804) comprises a sensor arranged to monitor for saturation of carbon dioxide. a) an input gas manifold comprising a plurality of valves (108, 110) and having at least one input that receives syngas (112, 328, 1806) and steam (114, 328, 1806); b) a pair of pressure vessels comprising a first and second pressure vessel (102, 104, 306, 308, 1202, 1708, 1708', 1802, 1804), each of the first and second pressure vessel comprising: i. a fixed bed of sorbent (106, 1100, 1204, 1712); ii. an input that is coupled to an output of the input gas manifold; and iii. an output; i. a fixed bed of sorbent (106, 1100, 1204, 1712); ii. an input that is coupled to an output of the input gas manifold; and iii. an output; c) an output gas manifold comprising a plurality of valves (122, 124) and having a first input that is coupled to the output of the first pressure vessel (102, 306, 1202, 1708, 1802) and a second input that is coupled to the output of the second pressure vessel (104, 308, 1804); d) a valve controller having at least one output that is coupled to the input gas manifold and at least one output that is coupled to the output gas manifold; and e) a compressor (120, 304, 1704) comprising an input port coupled to a port of the output gas manifold, the compressor being arranged to provide enough vacuum to the output gas manifold such that when the first or second pressure vessel exhausts CO 2 their partial pressure is below a decomposition line for calcium carbonate; characterised in that: the fixed bed of sorbent (106, 1100, 1204, 1712) comprises a lime, limestone honeycomb monolith comprising calcium aluminate and dolomite as additives that reduce the reaction time by increasing permeability of the fixed bed sorbent at high temperature; the pair of pressure vessels (102, 104, 306, 308, 1202, 1708, 1708' 1802, 1804) comprises a sensor arranged to monitor for saturation of carbon dioxide. the fixed bed of sorbent (106, 1100, 1204, 1712) comprises a lime, limestone honeycomb monolith comprising calcium aluminate and dolomite as additives that reduce the reaction time by increasing permeability of the fixed bed sorbent at high temperature; the pair of pressure vessels (102, 104, 306, 308, 1202, 1708, 1708' 1802, 1804) comprises a sensor arranged to monitor for saturation of carbon dioxide.