Direct synthesis of dimethyl ether (DME) from syn-gas was investigated over a series of hybrid catalytic systems containing Cu-based methanol synthesis component with varying amount of ZnO and MgO, and -Al 2 O 3 as a methanol dehydration component. Methanol synthesis and methanol dehydration components were homogeneously mixed in 2:1 weight ratio to prepare the hybrid catalysts, which were characterized by Transmission electron microscopy, Scanning electron microscopy, BET surface area analyzer, Powder X-Ray diffraction, NH 3-Temperature programmed desorption and H 2-Temperature programmed reduction methods. Syn-gas to DME (STD) reaction was studied in an isothermal fixed bed reactor at 30 bar and 260 C. The catalysis results revealed an improved effectiveness of the catalyst in the presence of 20 mol% MgO, enabling a significant enhancement in CO conversion from 19 to 37% and DME selectivity from 36 to 83%, when compared with the activity of a catalyst without MgO. By-products, CO 2 and C 1-C 2 hydrocarbons, selectivity were also decreased from 48 to 14% for CO 2 and from 8 to 2.5% for hydrocarbons. Catalyst performance, CO conversions and DME selectivity were evaluated by varying the reaction temperature, pressure, space velocity and H 2 /CO ratio in syn-gas. XRD data revealed the formation of a well crystalline malachite structure for the catalysts containing up to 20 mol% MgO, but the crystallinity in the structure lost when 30% MgO was added, resulting in a decreased catalytic activity.

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Thermodynamic modeling of gasification process provides a quick estimate of performance of the gasifier. Most of the earlier work on thermodynamic modeling is restricted to a particular feedstockÀgasification agent combination and hence the results cannot be generalized. In the present work, the equilibrium modeling based on Gibb's free energy minimization approach is used to analyze the performance of gasification of any fuel using oxygen or steam. The performance is analyzed at the carbon boundary point at which the cold gas efficiency is maximum. The gasification temperature, amount of gasification agent required, composition of syngas, and cold gas efficiency are predicted using Aspen Plus. The results are presented as contour plots on Van Krevelen coordinates (H/C vs O/C) and interpreted based on simplified gasification reactions. The performance for different feedstocks represented in Van Krevelen diagram is also analyzed. Finally, advantage of cogasification of feedstocks is highlighted.

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