Synthesis of Dimethyl Ether from CO₂ and H₂ Using a Cu–Fe–Zr/HZSM-5 Catalyst System

Abstract

The CuO–Fe2O3–ZrO2/HZSM-5 bifunctional catalyst was prepared and used for the direct synthesis of dimethyl ether (DME) from CO2 and H2. The results revealed that doping the CuO–Fe2O3 catalyst with ZrO2 might increase the specific surface area and change the chemical combination state of CuO by decreasing the outer-shell electron density of Cu via an obvious change in the interaction between CuO and Fe2O3. Addition of ZrO2 to the catalyst strongly affects the hydrocarbon selectivity. When using the CuO–Fe2O3–ZrO2/HZSM-5 bifunctional catalyst system, both the conversion of CO2 and the yield of DME were much higher than those obtained using CuO–Fe2O3/HZSM-5 as catalysts. Reactions carried out at 260 °C and 3.0 MPa with a gaseous hourly space velocity of 1500 mL·gcat –1·h–1 using CuO–Fe2O3–ZrO2/HZSM-5 with 1.0 wt % ZrO2 as the hydrogenation catalyst provided a 28.4% conversion of CO2 with 64.5% selectivity for DME.

Experimental and theoretical study of the intrinsic kinetics for dimethyl ether synthesis from CO2 over Cu–Fe–Zr/HZSM‐5

“…The Cu-Fe-Zr catalyst catalytically activates more CO 2 than the undoped catalyst, favoring an improvement in its ability to catalyze the hydrogenation of CO 2 to DME. 24 Adsorption state of CO 2 molecules on Cu(111) plane…”

“…Cu(NO 3 ) 2 Á3H 2 O and Fe(NO 3 ) 3 Á9H 2 O were weighed according to the Cu/Fe mole ratio of 3:2 and dissolved by deionized water followed by the addition of Zr(NO 3 ) 4 solution. The amount of the Zr(NO 3 ) 4 used depended on the desired ZrO 2 content of 1.0 wt % in CuO-Fe 2 O 3 -ZrO 2 (According to the literature, 24 the optimal doping amount of ZrO 2 found to be 1.0 wt %.). Under medium speed stirring, these nitrate solutions and a 1.0 molÁL 21 solution of Na 2 CO 3 were added to a beaker using a parallel flow coprecipitating method while maintaining at pH of 10 and a reaction temperature of 70 C for 2 h. After being aged for 1 h, the mixture was filtered and dried at 110 C for 12 h, ground to 20-80 mesh and calcined at 400 C for 4 h, and the CuO-Fe 2 O 3 -ZrO 2 catalyst was obtained.…”

“…The preparation detail of Cu-FeZr/HZSM-5 has been described previously in the literature. 24 Catalyst characterization H 2 -TPD and CO 2 -TPD experiments on the catalysts were performed using a PX200 multifunction catalyst analysis system (China Tianjin Golden Eagle Technology). For these analyses, 100 mg samples were reduced in situ at 300 C in a mixture of H 2 and Ar gases (8% H 2 ) at a flow rate of 30 mLÁmin 21 for 1 h, exposed to He (99.999%) flowing at 30 mLÁmin 21 for 1 h and then pumped to vacuum at 300 C for 1 h to remove any physically adsorbed species from the catalyst.…”

“…17,18 By considering recent research that used a CuO-ZnO-based catalyst in the catalysis of the one-step process 6,11 as well as reports of Cu-Fe-based catalysts that have been used to synthesize CO and CH 4 , 19,20 and taking into account the fact that ZrO 2 is often used as a textural promoter, 11,[21][22][23] a bifunctional catalyst was developed using CuO-Fe 2 O 3 -ZrO 2 as the methanol synthesis component and HZSM-5 as the methanol dehydration component. 24 Up until this point, studies regarding the kinetic aspects of DME synthesis have focused on its generation from syngas: Iliuta et al 25 have elucidated a model for DME synthesis in a fixed-bed membrane reactor, and Sierra et al 26 investigated the deactivation kinetics for direct DME synthesis on a CuO-ZnO-Al 2 O 3 /c-Al 2 O 3 catalyst, among other works. Conversely, there have been very few reports on the kinetics governing the directed hydrogenation of CO 2 to DME.…”

Ethanol as a Binder to Fabricate a Highly‐Efficient Capsule‐Structured CuO−ZnO−Al2O3@HZSM‐5 Catalyst for Direct Production of Dimethyl Ether from Syngas

“…[2][3][4][21][22][23][24][25][26][27][28][29][30] The hybrid catalysts prepared by physically mixing methanol synthesis catalyst (CuÀ ZnOÀ Al 2 O 3 ) and methanol dehydration catalyst (solid acid) were attempted to catalyze the STD process. [31][32][33][34][35][36][37][38][39][40] The methanol synthesis unit in the hybrid catalysts have been focused on tuning catalysts composition, [21][22][23][24][25] synthetic method, [26,27] preparation parameters of Cu-based catalysts [28,29] and alternatives to Cu-based. [30] The methanol dehydration unit in the hybrid catalysts has been focused on the modulation of particle size, [31] structure [32][33][34] and modification of acidic sites by metal [35][36][37][38] of zeolite and γ-Al 2 O 3 .…”