National General Energy Plan of Indonesia 2017 (RUEN 2017) stated that dimethyl ether (DME) is appointed as a blending of LPG to reduce LPG imports. DME can be made with two reaction pathways, namely direct synthesis and indirect synthesis. The objective of this study was to determine the effect of pressure and syngas composition on the direct synthesis of DME using dual fixed bed catalyst. The research was carried out with two types of catalyst: M-xxx as a commercial catalyst for methanol synthesis and γ-Al2O3 as catalyst for dehydration of methanol to DME. The later was prepared in our Laboratory of Chemical Reaction Engineering and Catalysis, ITB. The dual catalyst experiment was carried out at 5 and 7 bars, and a fixed temperature of 240oC. The mass ratio of the M-xxx to γ-Al2O3, so-called M/D ratios, were varied from 1/9 to 9/1. Two type of syngas were used, i.e. SA containing only H2 and CO with a SN of 2,3 and SB containing 4% CO2 with SN of 1,8. The dual bed with a M/D ratio of 1/4 gave a CO conversion up to 62% at 5 bars and 240oC (SA). As pressure increased, the conversion of CO and H2 increases to 85% and 83% at 7 bar and 240oC (SA). The presence of CO2 (SB) decreases catalyst activity, as indicated by the decrease in conversion of CO and H2 to 56% and 54%, at 7 bar and 240oC.

Dimethyl ether, direct synthesis, dual bed catalyst, stoichiometric number, γ-Al2O3

1. Akarmazyan, S. S., Panagioto- poulou, P., Kambolis, A., Papado- poulou, C. & Kondarides, D. I. (2014). Methanol dehydration to dimethylether over Al2O3 catalysts. Applied Catalysis B: Environmental, 145, 136-148.
2. Ardy, A., Rizkiana, J., Laniwati, M. & Susanto, H. (2019). Synthesis of dimethyl ether using a fixed bed of dual catalyst for methanol synthesis and its dehydration. MATEC Web Conf., 268, 07003.
3. Cai, M. (2015). Design of Novel Hybrid Catalysts for Direct Synthessis of Dimethyl Ether From Syngas. Doctor Universite de Lille.
4. Nagaraja, B. M., Siva Kumar, V., Shashikala, V., Padmasri, A. H., Sreevardhan Reddy, S., David Raju, B. & Rama Rao, K. S. (2004). Effect of method of preparation of copper – magnesium oxide catalyst on the dehydrogenation of cyclohexanol. Journal of Molecular Catalysis A: Chemical, 223, 339-345.
5. Peláez, R., Marín, P. & Ordóñez, S. (2017). Direct synthesis of dimethyl ether from syngas over mechanical mixtures of CuO/ZnO/Al2O3 and γ- Al2O3: Process optimization and kinetic modelling. Fuel Processing Technology, 168, 40-49.
6. Swastika, T., Ardy, A. & Susanto, H. (2019). Preparation of Catalyst Cu- ZnO-MgO-Al2O3 for Direct Synthesis of DME. IOP Conference Series: Materials Science and Engineering, 543, 012063.