Jurriaan Boon, Dr.

ECN / TU/e Modelling of CO2 Capture Processes - defense on July 4th, 2016

For pre-combustion  carbon capture, fuels are first converted to synthesis gas: CO and H2. Water-gas shift (WGS) is then applied to increase the CO2 and H2 content. CO2 is then separated; H2 is used for power production and CO2 can be stored underground. The high  partial pressure is a strong driving force for separation, allowing for relatively low energy use. Conventional processes for reaction and separation can be improved by processes based on CO2 adsorption with a solid sorbent or by H2 selective membranes. For both options, knowledge of the kinetics of CO2 capture and water-gas shift, as well as on transport limitations enables the design of efficient full scale reactors.

Sorbents

With a catalytically active high-temperature sorbent, a pressure swing process based on reversible CO2 adsorption at elevated temperatures (400°C) and pressures (10-30 bar) can be operated. Dynamic reactor modelling is needed for cycle design and scale-up. Key are the sorption kinetics and equilibrium Experiments are to be performed in ECN’s multi vessel test rig with six reactors of 6 m tall, enabling testing of process cycles and model validation.

Breakthrough experiments for a wide range of CO2 and H2O partial pressures will be analysed for amount adsorbed and uptake rate.

Membranes

Pd-alloy membranes are able to separate H2 from synthesis gas at elevated temperature (250-600°C) and pressure (30-40 bar). Membranes can be employed as separators, or may be used in a WGS reactor. 2D modelling is done to identify mass transfer resistances in bench-scale tests and to facilitate proper module design and scale-up. Experiments on ECN’s Process Development Unit (up to 8 membrane modules in parallel, allows testing of different module geometries) are used for ex-periments on H2 separation and combined WGS and H2 separation.

Starting with pure H2 flux measurements, the membrane permeance is quantified. Subsequently, the effects of feed gas constituents and sweep gases are tested.