One-Pot Synthesis of Cu–SO₄²⁻–ZrO₂ Catalysts for Use as Acid Catalyst in Dimethyl Ether Production from CO₂ Hydrogenation

The present research investigates the possibility of enhancing the stability of SO₄²⁻–ZrO₂ catalyst by adding Cu (2–12 wt%) prepared via a simple one-pot synthesis method. The substantial changes in the structures of Cu are observed which can be classified into two different ranges of Cu loading: 2–8 wt% and 10–12 wt%. Cu₂O is predominant phase at Cu loading of 2–8 wt%, which strongly interacts with ZrO₂, resulting in a decrease of number of acid sites and thus lowering DME yield compared to bare SO₄²⁻–ZrO₂. At Cu loading of 10–12 wt%, the predominant phase of Cu becomes CuSO₄ and the SO₄²⁻ from CuSO₄ may be formed as bridging S–O–S bonds with another S–O bonded to Zr atom_, resulting in the catalytic stability improvement. The optimum Cu loading is 10 wt% which attains the maximum DME yield of 3.2% at 260 °C and 20 bar.