Activity For Steam Reforming Of Methanol Research Articles

Performance of Cu/ZnO/Al2O3 Catalysts Prepared by Sol–Gel Methods on Methanol Steam Reforming

Cu/ZnO/Al2O3 catalysts were prepared for online methanol steam reforming (MSR) using a conventional sol–gel method in this study. The optimal preparation conditions, including the calcination temperature, Cu loading, molar ratio of citric acid to metal ions (CA/M), and pH, were investigated. CZA50 exhibited the highest MSR activity among all catalysts. It was prepared at a calcination temperature of 350 °C; Cu, Zn, and Al molar fractions of 50%, 30%, and 20%; CA/M of 1.5; and without adjusting pH. Furthermore, a modified sol–gel method was proposed to enhance the mechanical strength of Cu/ZnO/Al2O3 catalysts by using γ-Al2O3 powders as catalyst precursors instead of aluminum nitrates. In this modified method, part of Cu2+ and Zn2+ ions were impregnated firstly on γ-Al2O3 powders, and then the remaining metal ions formed sol–gel with citric acid. MCZA-0.25 catalysts prepared by this modified method showed superior catalytic activity at an Al/(Cu+Zn) ratio of 0.25. The methanol conversion rates of CZA50, MCZA-025, and CZA-Commercial were 82.9%, 79.4%, and 74.7% at the temperature of 200 °C and methanol liquid phase space velocity (LHSV) of 1.0/h, respectively. The average crushing strength of CZA50, MCZA-0.25, and CZA-Commercial were measured as 28 N/cm, 37 N/cm, and 32 N/cm, respectively.

An InOx Surface Enrichment on the Cu Nanoparticles for the Methanol Steam Reforming

AbstractIn the realm of heterogeneous catalysts promoted by indium, indium often covers other active metals, thereby compromising catalytic activity. However, the inhibition mechanism remains poorly understood. In this study, we investigate the interaction between copper (Cu) and indium oxide (InOx), focusing on the role of the Cu−In interface during the methanol steam reforming (MSR) reaction. Utilizing a series of (quasi) in situ characterization techniques, we observe a decrease in intrinsic catalytic activity for MSR on the CuIn/Al2O3 catalyst, which can be attributed to the surface enrichment of InOx on Cu nanoparticles. Moreover, our findings reveal that the enrichment suppresses both the dehydrogenation of *CH3O and the dissociation of H2O, ultimately leading to a reduction in catalytic activity. This discovery has the potential to guide the rational design of enhanced indium‐based catalysts in the future.

Enhanced metal−promoter interaction over Na modified Co2C nanoprisms for high-efficiency hydrogen production from methanol steam reforming

As an important application for methanol-based energy-storage systems, methanol steam reforming (MSR) using appropriate catalysts can provide clean hydrogen via onboard production for fuel cells. However, owing to their unsatisfactory activity and stability, the use of the most common catalysts, including Cu-based and groups 8–––10 transition metals, remains challenging. Herein, a series of Na-promoted Co2C nanoprism catalysts containing different Na loadings was used for the first time in MSR. The 1Na/Co2C catalyst showed an excellent activity and stability for MSR, with H2 production rates as high as 4637.9 μmol/gcat/min at 250 °C, which outperforms most of the reported catalysts. In-depth characterizations revealed that a strong interaction between Na and Co2C stabilized the catalyst and promoted the dissociation of CH3OH and H2O. A further investigation of the reaction mechanism revealed that the reaction proceeded via the dehydrogenation of methanol and sequential water−gas shift reactions. Density functional theory calculations revealed that the Co2C (101) surface exhibited the lowest energy barrier and that the methoxy dehydrogenation was the rate-determining step. This work provides further valuable insights into the rational design of transition-metal carbide catalysts for MSR.

Steam reforming of methanol for hydrogen production over attapulgite-based zeolite-supported Cu-Zr catalyst

The methanol steam reforming (MSR) was one of the promising technologies for high-efficiency hydrogen production. The key issue for MSR was the development of catalysts. In this paper, the Cu-Zr components supported on the attapulgite-based zeolite (AZ) was prepared and applied into MSR reaction. MSR activity test demonstrated the synthesized micropore and mesopore channels in AZ enhanced the catalytic performance through promoting the heat and mass transfer. Various characterizations such as N2 adsorption–desorption, XRD, H2-TPR, XPS, SEM, HRTEM, H2/CO2-TPD, H2 pulse chemisorption and TGA confirmed Zr addition significantly increased the distribution of active metal particles and metallic surface area and facilitated the formation of Cu0/Cu+-ZrOxHy interface sites. Among the prepared catalysts, 1Cu1Zr/AZ catalyst possessed the maximum Cu0/Cu+-ZrOxHy interface sites and metallic surface area, therefore it exhibited the best catalytic performance for MSR, and its hydrogen productivity reached to 655.1 mmol/gcat/h. In addition, the Cu0/Cu+-ZrOxHy interface sites in Zr-modified Cu/AZ catalysts inhibited the active metal sintering and coke formation. The possible mechanism of MSR over 1Cu1Zr/AZ was proposed, in which Cu0/Cu+ species promoted the decomposition of methanol and intermediates, meanwhile, the Cu0/Cu+-ZrOxHy interface sites helped to continuously provide the –OH groups through steam activation by hydroxylated Zr species. These cooperative effects promoted the oxidation of intermediates and water–gas shift reaction, resulting in producing more H2 and CO2. This work offers a possibility for preparing available and economical attapulgite-based zeolite-supported Cu-Zr Catalyst for MSR.

The influence of the support composition on the physicochemical and catalytic properties of Cu catalysts supported on Zirconia-Alumina for methanol steam reforming

ZrAl materials with different compositions have been synthesized by the hydrothermal method and used as supports of Cu catalysts for hydrogen production from methanol steam reforming (MSR). The effect of the support composition, Zr/Al ratio, on the physicochemical and catalytic properties of CuZrAl catalysts was studied. The characterization results show that there is an optimal support composition (Zr/Al ratio of 0.4), allowing to achieve the highest methanol conversion due to enhanced dispersion and reducibility of copper. Zr-rich catalysts displayed low MSR activity, which is likely due to the segregation and crystallization of zirconia, resulting in the formation of large copper particles with lowered dispersion and reducibility. The catalyst with the optimal Zr/Al ratio shows the highest methanol conversion, enhanced selectivity and good long term stability, rendering this catalyst a promising material for the production of high purity H2 from MSR.

Low-temperature hydrogen production from methanol steam reforming on Zn-modified Pt/MoC catalysts

Methanol steam reforming (MSR) is a promising process to produce hydrogen suitable for polymer electrolyte membrane fuel cells, but the development of catalysts with high activity and selectivity at low temperature is highly needed. Here, a series of Zn-modified Pt/MoC catalysts with different Zn loadings were prepared and used to produce hydrogen by MSR at low temperature. The addition of small amounts of Zn to Pt/MoC not only favors the formation of α-MoC1-x phase, but also enhances the Pt dispersion and the interaction between α-MoC1-x and Pt active sites, leading to increased catalytic activity for MSR. The optimal 0.5Zn-Pt/MoC catalyst exhibits superior hydrogen production activity with exceptionally low CO selectivity at low temperatures (120–200 °C). Overall, this work offers insight into the structure-activity relationship and stability in Zn-modified Pt/MoC catalysts for MSR, which will be helpful to the design of MSR catalysts with high activity and stability at low temperature.

Hydrogen production from methanol steam reforming catalyzed by Fe modified Cu supported on attapulgite clay

A series of Cu catalysts supported on attapulgite (ATP) clay modified by Fe were synthesized by impregnation method and employed to investigate the catalytic performance for hydrogen production by methanol steam reforming (MSR) in the range of 240–315 °C. The physicochemical characteristics of Fe modified Cu catalysts supported on ATP were tested by N2 adsorption, XRD, SEM, H2-TPR, CO2-TPD and NH3-TPD. An excellent MSR activity, high methanol conversion and high selectivity of H2 with ignorable CO content, was achieved on Fe modified Cu/ATP catalysts. The presence of Fe promotes the reduction of CuO to metal Cu and improves the dispersion of Cu on ATP due to the synergistic effects between CuO and Fe2O3, which contribute to the high activity for MSR. ATP, as an easily available and cheap material, is a promising support of Cu-based catalysts for hydrogen production from methanol steam reforming.

First-Principles and Microkinetic Simulation Studies of the Structure Sensitivity of Cu Catalyst for Methanol Steam Reforming

High CO2 and H2 selectivity are important issues for methanol steam reforming (MSR) to provide H2 as a clean energy carrier. The structure sensitivity and the factors governing the activity and selectivity for MSR on Cu catalysts are systematically investigated using density functional theory calculations and microkinetic simulation. Potential energy surfaces including water dissociation, methanol dehydrogenation, formaldehyde desorption and coupling with oxygen-containing intermediates, and formation of hydrogen and carbon dioxide are calculated over Cu(111), (100), (221), (211), and (110) surfaces, respectively. It is found that Cu(110) facet is the most active and selective toward carbon dioxide; Cu(221) is also active but highly selective toward formaldehyde, whereas Cu(111) is nearly inactive. Degree of rate control analysis shows that the activity is controlled mainly by methanol dehydrogenation to formaldehyde, whereas the degree of selectivity control shows that the selectivity toward formaldehyde...

Combustion synthesized copper-ion substituted FeAl2O4 (Cu0.1Fe0.9Al2O4): A superior catalyst for methanol steam reforming compared to its impregnated analogue

A series of copper ion substituted MAl2O4 (M = Mg, Mn, Fe and Zn) spinels is prepared by a single step solution combustion synthesis (SCS) and tested for methanol steam reforming (MSR). The copper ion substituted Cu0.1Fe0.9Al2O4 appears to be the most active, showing ∼98% methanol conversion at 300 °C with ∼5% CO selectivity at GHSV = 30,000 h−1 and H2O:CH3OH = 1.1. The analogous impregnated catalyst, CuO (10 at%)/FeAl2O4, is found to be much less active. These materials are characterized by XRD, H2-TPR, BET, HRTEM, XPS and XANES analyses. Spinel phase formation is highly facilitated upon Cu-ion substitution and Cu loading beyond 10 at% leads to the formation of CuO as an additional phase. The ionic substitution of copper in FeAl2O4 leads to the highly crystalline SCS catalyst containing Cu2+ ion sites that are shown to be more active than the dispersed CuO nano-crystallites on the FeAl2O4 impregnated catalyst, despite its lower surface area. The as prepared SCS catalyst contains also a portion of copper as Cu1+ that increases when subjected to reforming atmosphere. The MSR activity of the SCS catalyst decreases with time-on-stream due to the sintering of catalyst crystallites as established from XPS and HRTEM analyses.

Single step combustion synthesized Cu/Ce0.8Zr0.2O2for methanol steam reforming: structural insights fromin situXPS and HRTEM studies

AbstractSingle step combustion synthesized Cu (5–15 at.-%)/Ce0.8Zr0.2O2 materials containing highly dispersed copper have been assessed for methanol steam reforming (MSR). The activity patterns suggest Cu (10 at.-%)/Ce0.80Zr0.20O2 as the most active formulation, converting ~51% methanol at 300 °C at a gas hourly space velocity of 40,000 h-1 (W/F = 0.09 s). The in situ XPS experiments carried over the most active sample show a sharp falloff of Cu-surface concentration from a considerably high value of 26% before to 7.4% after the in situ MSR tests and it is associated with the complete reduction of oxidized Cu-species (Cu2+) to metallic copper (Cu0). These findings point to the sintering of copper during MSR which is attributed to be responsible for the deactivation observed with time on stream. Interestingly, the MSR activity is shown to be regenerated nearly completely through an intermediate in situ oxidation step in the consecutive cycles of methanol reforming.

Cu–Cr, Cu–Mn, and Cu–Fe Spinel-Oxide-Type Catalysts for Reforming of Oxygenated Hydrocarbons

Effective hydrogen production is achieved via steam reforming of the oxygenated hydrocarbons, including methanol and dimethyl ether, over Cu-based spinel-oxide catalysts. CuFe2O4, CuMn2O4, and CuCr2O4 were well-crystallized in spinel structures and were provided with low specific surface areas below 2 m2 g–1. Upon reduction, the spinels possessed Cu+-rich surfaces when compared with a commercial Cu/ZnO/Al2O3, which resulted in better catalytic performance in methanol steam reforming (MSR). The composite catalysts of the Cu spinel and γ-Al2O3 were promising for dimethyl ether steam reforming (DMESR) in terms of activity, selectivity, and stability. The descending order of the DMESR activity over the composite catalysts was as follows: CuFe2O4–γ-Al2O3 > CuMn2O4–γ-Al2O3 > CuCr2O4–γ-Al2O3, which was in line with the MSR activity over Cu–spinel catalysts. This revealed that the MSR activity strongly contributed to the high DMESR activity using the composite Cu–spinel catalysts and γ-Al2O3. The theoretical calc...

High CO2 Selectivity of ZnO Powder Catalysts for Methanol Steam Reforming

To investigate the contribution of the ZnO supports in PdZn/ZnO catalysts used for methanol steam re-forming (MSR), we have investigated methanol steam re-forming on two different ZnO powder samples. The powder samples included a commercial powder with both polar and nonpolar surfaces exposed, and a plate-like sample preferentially exposing the polar ZnO(001)/ (001̅) surfaces. ZnO was found to be active and selective for MSR, with the polar surfaces being most active, but the activation energy for reaction (∼100 kJ/mol) was much larger than on unsupported PdZn(∼50 kJ/mol) or PdZn/ZnO. The experimental findings are supported by DFT calculations on key elementary steps and reaction intermediates on the ZnO(001) surface. We conclude that the contribution of the ZnO support to the MSR activity PdZn/ZnO catalyst system may not be very significant.

The Role of the Promoters in Cu Based Catalysts for Methanol Steam Reforming

Effects of promoters such as zirconia and zinc oxide to copper catalysts have been studied in methanol steam reforming (MSR) reaction at 260 °C. The catalytic activity and stability of copper are improved by promoters, especially zirconia. The results of S BET and S Cu represent that both promoters can increase S BET of catalysts from 0.26 to 0.28–0.99 m2/g and S Cu of them from 0.13 to 0.21–0.25 m2/g and XRD further illustrate that they can stabilize the crystal size of copper in process of reduction and reaction. Besides, XPS results indicate that both ZnO and ZrO2 can stabilize Cu+ species and promote the catalytic activity for MSR. In addition, the rich surface hydroxyl species on ZrO2/Cu account for its superior catalytic performance to ZnO/Cu and Cu.