Fig. 3. Effect of Zn/Zr molar ratio on catalytic behaviours of the bifunctional Zn–ZrO₂/H–SSZ-13–45H catalyst. The selectivity of CO₂ did not change with the ratio of Zn/Zr and was in the range of 41–45% for each catalyst. Reaction conditions: catalyst, 0.60 g; H₂/CO = 2; P = 3 MPa; T = 673 K; F = 30 mL min^–1; time on stream, 10 h.