Laboratory- and bench-scale studies of a sweet water–gas-shift catalyst for H2 and CO2 production in pre-combustion CO2 capture

In the first section of this paper, the activity of an iron–chromium-based catalyst for the water–gas-shift reaction is studied at laboratory scale. The influence on the activity of the sweet shift catalyst of the main operating parameters-temperature, space velocity, excess steam, pressure, and gas composition-is evaluated. Base case gas composition M1 was set according to that of the IGCC Power Plant of Puertollano, Spain (ELCOGAS): N2 13.4 vol%, CO 60.7 vol%, H2 22.3 vol%, and CO2 3.6 vol%. The effect of gas hourly space velocity GHSV (2000–5000 h−1), steam to CO ratio R, (1–3 mol mol−1), pressure P (0.1–2 MPa), and temperature (523–653 K) has been determined. In order to study the effect of gas composition on the activity of the WGS catalyst, the following gas mixtures have been evaluated: M2 (CO 60.7 vol%, H2 22.3 vol%, and CO2 17 vol%); M3 (CO 60 vol%, N2 40 vol%); and M4 (CO 60 vol%, and CO2 40 vol%).The second part of this paper deals with subsequent WGS testing at bench-scale level, based on the results obtained at laboratory scale. Tests were performed using a gas composition according to that of ELCOGAS IGCC plant. The operating temperature was 583 K, pressure was set at 1 MPa, and gas space velocity was 4715 h−1. The effect of steam to CO ratio was evaluated.

► Study of activity of a WGS Fe-based catalyst under coal-derived syngas conditions. ► CO content decreased from 60 vol% to 3 vol% and H2 increased up to 50 vol% (d.b.). ► Conversion improved on increasing temperature up to 653 K and at low space velocity. ► More steam enhanced CO conversion, while it worsened above 573 K for CO2-rich gas. ► Good performance at 4715 h−1, 583 K and H2O/CO = 1.6–3 during bench-scale tests.