Kinetic modelling of dimethyl ether synthesis from (H2+CO2) by considering catalyst deactivation

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

“…In the catalytic CO 2 hydrogenation to DME, a CuFe-Zr/HZSM-5 dual-function catalyst was used for CO 2 hydrogenation, with the target products being DME and methanol; the expected by-products are CO and CH 4 . Due to the reaction energy barrier of CH 4 formation being less than those of DME and methanol formation, as well as that of the reverse water-gas reaction, 6 and considering that the observed CH 4 yield is less than 1%, CH 4 synthesis is considered to be balanced with the reaction of CO 2 hydrogenation to DME.…”

“…The active sites and the rate-limiting step of the methanol synthesis reaction are still controversial. Numerous studies 6,[25][26][27][28][29] show that Cu is the main active site in methanol synthesis over Cu-based catalysts and that when doped by other metal oxides, the dispersion, stability, and electronic properties of copper active sites can be altered, improving the activity of Cu and leading to improved catalytic performance of the copper-based catalyst. According to the results of H 2 -TPD and CO 2 -TPD presented earlier, H 2 adsorbs easily to Cu whereas CO 2 adsorption onto Cu is weak at 240-280 C and is primarily achieved by adsorption to Fe and subsequent desorbed and moved to Cu.…”

“…In this case, the thermodynamic equilibrium of the methanol synthesis process is broken, 6,7 allowing for a higher conversion rate per pass; 8 additionally, the combination of both steps into one improves the driving force of the reaction 7,9 and from an economic perspective, lowers the cost of equipment for large-scale synthesis. 10 For all of these reasons, the one-step process is the primary focus of developmental research into DME synthesis from CO 2 .…”

“…Conversely, there have been very few reports on the kinetics governing the directed hydrogenation of CO 2 to DME. Through the study of kinetic models, McBride et al 27 found that a layered catalyst arrangement significantly changes CO conversion as well as methanol and DME yield compared with a physical catalyst mixture, while Ereña et al 6 considered deactivation of a CuO-ZnO-Al 2 O 3 /c-Al 2 O 3 catalyst during DME synthesis, and Zeng and coworkers 28,29 studied the intrinsic kinetics of DME synthesis directly from CO 2 hydrogenation over a Cu-ZnO-SiO 2 /HZSM-5 and a CuZnO-Al 2 O 3 /HZSM-5 catalyst. However, the reaction mechanism and the intrinsic kinetics model of CO 2 catalyzed hydrogenation to DME over Cu-or Cu-Zn-based catalysts are still uncertain, and the conversion of CO 2 and the selectivity of DME in general are still very low, and need to be improved.…”

“…However, DME synthesis generates more water than methanol synthesis alone, and as such, the activity and stability of catalysts could be adversely affected by the hydrophilicity of ZnO. 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.…”