Direct synthesis of dimethyl ether on the admixed nanocatalystsof CuO–ZnO–Al2O3 and HNO3-modified clinoptilolite at high pressures: Surface properties and catalytic performance

The potential of clinoptilolite as a methanol dehydration catalyst in direct conversion of syngas to dimethyl ether has been investigated. The modified form of clinoptilolite was obtained by nitric acid treatment. Although the physicochemical analysis showed that crystallinity of the clinoptilolite decreased during HNO3-treatment, the specific surface area of natural zeolite increased considerably. Size distribution histogram of the synthesized nanocatalyst showed that the particle size of active phase was between 28.9 and 112.9 nm with an average size of 53.9 nm. The NH3-TPD profiles showed that both the number and strength of the acid sites of the CuO–ZnO–Al2O3/clinoptilolite nanocatalysts decreased with increasing active phase content. Results indicated that the optimal reaction temperature and pressure for this nanocatalysts were 300 °C and 40 bar, respectively. The catalytic performance of synthesized samples showed that the optimum CuO–ZnO–Al2O3 to clinoptilolite ratio was 4:1, which depends on temperature and pressure.

The potential of clinoptilolite as a methanol dehydration catalyst in direct syngas to dimethyl ether conversion has been investigated. The modified form of clinoptilolite was obtained by nitric acid treatment. In order to address the effect of various ratios of CuO–ZnO–Al2O3 to clinoptilolite on the catalytic performance of the hybrid catalyst, a series of CuO–ZnO–Al2O3/clinoptilolite nanocatalyst with different active phase content were successfully synthesized via co-precipitation method. The influence of reaction temperature and pressure was investigated in detail, confirming that the optimal reaction temperature and pressure for this catalyst were 300 °C and 40 bar, respectively. The catalytic performance is shown the optimum value for the composition of CuO–ZnO–Al2O3/clinoptilolite nanocatalysts has been 4:1, which could be depended on temperature and pressure.Figure optionsDownload as PowerPoint slideHighlights
► Successful employing of CuO–ZnO–Al2O3/clinoptilolite in direct synthesis of DME from syngas.
► Potential employing of clinoptilolite in direct synthesis of DME from syngas.
► Optimum ratio of CuO–ZnO–Al2O3/clinoptilolite is 4:1 in direct synthesis of DME.
► Particle size distribution of 28.9–112.9 nm with an average size of 53.97 nm.
► Optimal reaction temperature and pressure for CuO–ZnO–Al2O3/clinoptilolite were 300 °C and 40 bar.