Long carbon nanotubes intercrossed Cu/Zn/Al/Zr catalyst for CO/CO2 hydrogenation to methanol/dimethyl ether

Vertically aligned carbon nanotube (CNT) arrays were dispersed in Na2CO3 solution and co-precipitated with metal nitrite to form long CNTs (over 500 μm) intercrossed Cu/Zn/Al/Zr catalyst (CD703). The catalyst was used for methanol synthesis from CO/CO2 hydrogenation. The space time yield (STY) of methanol on CD703 increased to 0.94 and 0.28 g/(gcat h), with an increment of 7% and 8% compared with that on the Cu/Zn/Al/Zr catalyst without CNTs for CO and CO2 hydrogenation, respectively. Furthermore, when combined with γ-Al2O3 catalyst and HZSM-5, dimethyl ether (DME) was obtained with a STY of 0.90 and 0.077 g/(gcat h) at 270 °C from one step CO and CO2 hydrogenation, respectively. Due to the phase separation, ion doping and valence compensation, hydrogen reversibly adsorption and storage on CNTs promoting hydrogen spillover, CD703 catalyst show good activity for methanol synthesis. Owing to the high thermal conductivity of CNTs, the stability of CD703 was improved. This indicated that long CNTs were a good promoter on the Cu/Zn/Al/Zr catalyst for methanol/DME production from CO/CO2 hydrogenation.