Catalysts For Carbon Dioxide Reforming Research Articles

NiO-MgO Prepared by the Complex-Decomposition Method as a Catalyst for Carbon Dioxide Reforming of Methane

The NiO-MgO solid solution has been proven to be an efficient catalyst for the carbon dioxide reforming of methane (CRM). However, the challenge is still there for the facilely controlled synthesis of the single-phase solid solution with the uniform composition, and the interactions between NiO and MgO are not consistently correlated with the CRM performance. To address these issues, in this work, the complex-decomposition method was applied to regulate the chemical and structural properties of NiO-MgO catalysts via simply changing the complexing agent, calcination temperature, and Ni/Mg molar ratio. The catalysts were comparatively evaluated for CRM under severe reaction conditions of 750 °C, 0.1 MPa, CH4/CO2 = 1, and a gas hourly space velocity of 60000 mL·g−1·h−1. Irrespective of the complexing agents investigated, NiO-MgO solid solution was exclusively formed. However, the structural and reductive properties of the NiO-MgO catalysts were strongly dependent on the complexing agent, which is reasonably explained as the varied coordinative capabilities of the complexing agent with the metal cations. Moreover, the highest CRM performance, i.e., the initial CH4 conversion of ~86% kept constant for a time-on-stream of 20 h, was achieved over the Ni0.1Mg0.9O catalyst by using glycine as the complexing agent and calcined at 800 °C. The characterization and CRM results vigorously confirmed that a good balance between the sintering and the in situ release of active metallic Ni under CRM reaction conditions was constructed over the NiO-MgO catalyst prepared using glycine as the complexing agent, leading to its highest stability. Considering the simple procedure of the complex-decomposition method and the convenient adjustment of the NiO and MgO interactions by simply changing the complexing agent and calcination temperature, the thus developed catalyst can be applied for extensive understanding the CRM mechanism, and extended for large-scale preparation.

Sintering- and coking-resistant nickel catalysts embedded in boron nitride supported nickel aluminate spinels for dry reforming of methane

Dry reforming of methane (DRM) showed prospective to reduce greenhouse gas emissions if the sintering- and coking-resistant Ni-based catalysts were successfully developed. In this work, emergent Ni nanoparticles embedded in boron nitride supported nickel aluminate spinels were originally developed for DRM. The acidity and basicity derived from nickel aluminate spinels could enhance the decomposition of CH4 and adsorption of CO2, respectively, which provides an ensemble effect with emergent Ni nanoparticles and cooperatively enhances the intrinsic activity. Moreover, the strong metal-support interaction derived from exsolution effects as well as the increased contact interface between nickel aluminate spinels and boron nitride would suppress the metal sintering while the boron nitride could inhibit the carbon deposition. The two-dimensional Raman spectra demonstrated the deposited carbon featured with low graphitic degree in the catalysts. This work provides a novel approach for the development of sintering- and coking-resistant Ni-based catalysts for carbon dioxide reforming of methane.

Nickel on two-dimensional ITQ-2 zeolite as a highly active catalyst for carbon dioxide reforming of methane

The physicochemical properties of the support material are important parameters that determine the activity and stability of supported metal catalysts in chemical reactions. In this study, we investigated the influence of the support dimensionality and nickel loading (5, 15, and 30 wt%) of supported-Ni catalysts for the carbon dioxide reforming of methane (CDR) by comparing the three-dimensional (3D) Ni/MCM-22 and its delaminated two-dimensional (2D) Ni/ITQ-2 catalyst. Owing to its delaminated nature, Ni/ITQ-2 exhibited a large external surface area (319 m2 g−1) and a high proportion of the nickel phyllosilicate phase, even for 30 wt% Ni loading. In addition, the strong interaction of Ni clusters with phyllosilicate resulted in a high dispersion of Ni. The 2D Ni/ITQ-2 catalysts generally exhibited a higher catalytic performance than the 3D Ni/MCM-22 catalysts. The relative proportion of the nickel phyllosilicate phase in the catalyst also played a promoting role in achieving a high catalytic performance for CDR. Unlike Ni/γ-Al2O3, Ni/ITQ-2 exhibited high conversions of CH4 and CO2, regardless of pre-reduction, which is advantageous for catalyst handling.

Effect of titania synthesis conditions on the catalytic performance of mesoporous Ni/TiO2 catalysts for carbon dioxide reforming of methane

The catalytic performance of 5 wt% Ni/TiO 2 catalysts with different physicochemical properties was studied for the CO 2 reforming of methane reaction. The TiO 2 supports were prepared by the evaporation-induced self-assembly method using three different titania metal precursors. The catalysts were characterized by XRD, BET, TGA, and TEM techniques. The results showed that the phase composition of TiO 2 support plays a crucial role in catalyst performance. Furthermore, the variation of synthesis conditions significantly affects the physicochemical properties of TiO 2 support. NH 3 -treatment helped maintain the higher surface area by retaining a significant fraction of the amorphous content of titania support. Catalysts deactivation was caused by the phase transformation of TiO 2 from anatase to rutile and the sintering of Ni metal. Phase transformation into rutile was more significant, with the catalysts possessing a higher content of amorphous TiO 2 . Ni/TiO 2 catalyst prepared using the titanium ethoxide precursor performed better in the dry reforming reaction. Anatase titania offers strong metal-support interaction, whereas weak metal-support interaction was observed in the amorphous and rutile phase. • TiO 2 support samples of distinctive physicochemical properties were prepared by varying the synthesis conditions. • Effect of Physico-chemical properties of Ni/TiO 2 catalysts was observed for the dry reforming reaction. • The Ni/TiO 2 catalyst synthesized from titanium ethoxide precursor showed good coke resistance. • The amorphous TiO 2 phase showed low metal-support interaction. • The phase content and the textural properties of TiO 2 can be tuned by varying the synthesis conditions.

Development of nanocrystalline mesoporous Pt promoted Co-based catalysts for carbon dioxide reforming of methane

In this study, a series of mesoporous Co-Pt/TiO2-Al2O3 catalysts were synthesized and evaluated for CO2 reforming of methane for synthesis gas production. The physicochemical properties of catalysts were assessed using various analytical techniques. Results showed higher activity and stability for bimetallic Co-Pt/TiO2-Al2O3 catalysts than the corresponding monometallic catalysts. The synergistic combination of Co and Pt, with the TiO2 mixed oxide support, results in the fine-tuned catalysts for the sustainable production of syngas. The TiO2 supported catalysts didn't show any deposition of hard carbon. TiO2-Al2O3 support excellently prohibits the carbon deposition and sintering of metal up to 10 wt% of Co active metal loading. Further increasing the metal loading resulted in the deactivation of catalyst by coke deposition. The study revealed that the 5 wt% Co- 0.5 wt% Pt/TiO2-Al2O3 catalyst is an excellent catalyst for the dry reforming reaction. The fine distribution of Pt alongside Co metal in the bimetallic system promotes the dry reforming reaction. The maximum syngas production rate of 72 mL g−1 h−1 with 65% to 85% of reactants conversions was obtained at 700 °C and 1 bar. The generation of Co2+ species in Co/Al2O3 catalyst was the reason for activity loss, whereas the mixed oxide support supremely prevented the formation of Co2+ species.

The Effect of Preparation Method of Ni-Supported SiO2 Catalysts for Carbon Dioxide Reforming of Methane

Reforming methane to produce syngas is a subject that generates considerable interest. The process requires catalysts that possess high-performance active sites to activate stable C–H bonds. Herein, we report a facile synthetic strategy to prepare Ni-based catalysts by complexation–impregnation (Ni-G/SiO2-C) and precipitation–impregnation (Ni-G/SiO2-P) methods using glycine as a complexing agent. The particle size of Ni in both types of catalysts is decreased by adding glycine in the preparation process. Nevertheless, the preparation methods and amount of glycine play a significant role in the particle size and distribution of Ni over the Ni-based catalysts. The smaller particle size and narrower distribution of Ni were obtained in the Ni-G/SiO2-P catalyst. The catalysts were comparatively tested for carbon-dioxide reforming of methane (CDR). Ni-G/SiO2-P showed better CDR performance than Ni-G/SiO2-C and Ni/SiO2 and increased stability because of the smaller particle size and narrower distribution of Ni. Moreover, a high-performance Ni-based catalyst was prepared by optimizing the amount of glycine added. An unobservable deactivation was obtained over Ni-G-2/SiO2-P and Ni-G-3/SiO2-P for CDR during TOS = 20 h. Thus, a new promising method is described for the preparation of Ni-based catalysts for CDR.

Nickel on Two-Dimensional ITQ-2 Zeolite as a Highly Active Catalyst for Carbon Dioxide Reforming of Methane

Nickel on Two-Dimensional ITQ-2 Zeolite as a Highly Active Catalyst for Carbon Dioxide Reforming of Methane

CeO2-Promoted Ni/SiO2 Catalysts for Carbon Dioxide Reforming of Methane: The Effect of Introduction Methodologies

Three typical methods, subsequent coating, co-impregnation and sequential impregnation, were employed to investigate the effect of introduction methodologies for CeO2-promoted Ni/SiO2 catalysts. The CeO2@Ni/SiO2 catalyst prepared with the subsequent coating method was found to exhibit the best initial activity and superior long-term stability in CO2 reforming of methane. Comparative characterizations documented that small Ni size and intimate Ni–CeO2 contact were generated on the CeO2@Ni/SiO2 catalyst, leading to excellent reforming activity. In addition, pronounced redox property and strong surface basicity were created on the CeO2@Ni/SiO2 catalyst, resulting in exceptional coke resistance and thus superior long-term stability. This work unravels the impact of various introduction methods on the catalyst structure, which would help design robust nanocomposite catalysts with outstanding catalytic performance.

A short review on bimetallic Co-based catalysts for carbon dioxide reforming of methane

Abstract The development of catalysts that afford excellent catalytic performance along with high resistance toward coke accumulation is fundamental in carbon dioxide reforming of methane (CDRM). Apart from Ni-based catalysts, the Co-based catalysts gained significant attention in CDRM accredited to the Co’s capability in improving catalytic stability and lowering the coke formation. However, the lower catalytic activities of Co-based catalysts when compared to Ni-based catalysts in reforming works are the real challenges that need to be solved. In this study, a short review of various approaches that have been implemented by researchers for improving the catalytic performance issues related to Co-based catalysts is presented. This paper also presents recent Co-bimetallic catalysts approached, covers the catalyst activity as well as issues related to catalyst deactivation when compared to Co monometallic catalysts. In addition, the outlook of the related bimetallic Co-based catalysts has been proposed to provide more critical information.

Customized Ni–MgO–Al2O3 catalyst for carbon dioxide reforming of coke oven gas: Optimization of preparation method and co-precipitation pH

• A Ni–MgO–Al 2 O 3 catalyst was customized for CO 2 reforming of coke oven gas. • Co-precipitation was selected as the optimum catalyst preparation method. • The co-precipitated pH was optimized as 12.0. • Complex NiO species–support interactions were key for catalytic activity. • The optimized catalyst lowered the H 2 /CO ratio of coke oven gas from 7.00–1.66. Coke oven gas can be upgraded through catalytic reforming using carbon dioxide as a soft oxidant. Herein, a customized Ni–MgO–Al 2 O 3 catalyst for the carbon dioxide reforming of coke oven gas was developed by selecting an appropriate catalyst preparation method and further optimizing the key variable of the selected method. Catalysts were prepared by various methods including co-precipitation, incipient wetness impregnation, hydrothermal, co-impregnation, and sequential impregnation. Among them, the co-precipitated catalyst showed the best performance. As the key variable, the co-precipitated pH of the precursor solution was optimized as 12. The catalysts were characterized using X-ray diffraction, Brunauer–Emmet–Teller method, H 2 –temperature-programmed reduction, H 2 –chemisorption, and thermogravimetric analysis. The interaction between a complex NiO species and the support material showed a strong relationship with the number of Ni° active sites, which also has a direct connection with the activity of the catalyst. The developed catalyst successfully lowered the high H 2 /CO ratio of coke oven gas from 7.00–1.66 through the carbon dioxide reforming reaction. Moreover, the catalytic activity was maintained over 50 h and thermodynamic equilibrium was achieved, even at a high gas hourly space velocity of 600,000 h −1 .

Ni–Fe/Mg(Al)O alloy catalyst for carbon dioxide reforming of methane: Influence of reduction temperature and Ni–Fe alloying on coking

Various Ni–Fe/Mg(Al)O alloy catalysts were obtained by calcination of Ni–Fe–Mg–Al hydrotalcite-like compounds, followed by reduction at different temperatures (973–1173 K). The characterizations of XRD and STEM-EDX suggest that the resulting Ni–Fe alloy particles are composition-uniform and size-controllable. The alloy composition is little affected by the reduction temperature, whereas the particle size (5.8–8.2 nm) increases with the increase of reduction temperature. This property is ascribed to the homogeneous distribution of nickel and iron species during the catalyst preparation. All of the Ni–Fe/Mg(Al)O alloy catalysts show relatively high and stable activity for CH4–CO2 reforming during 25 h of investigation at 773–1073 K. Particularly, the 973 K-reduced catalyst exhibits higher coke-resistance due to its smaller particle size. Ea-CH4 and CH4-TPSR measurements indicate that Ni–Fe alloying inhibits CH4 dissociation. It is considered that during DRM CH4 is dissociated at the Ni sites and CO2 may be activated at the metal-support interface as well as the Fe sites. Ni–Fe alloying may inhibit CH4 dissociation and/or promote CO2 activation, thus contributing to the suppression of coke deposition.

Reducible oxide (CeO2, ZrO2, and CeO2-ZrO2) promoted Ni-MgO catalysts for carbon dioxide reforming of methane reaction

Ni-MgO catalysts have been widely applied for carbon dioxide reforming (CDR) reaction due to their ability of anti-carbon formation. However, activation of Ni-MgO catalyst consumes considerable energy because of its very low reducibility. In this study, ZrO2, CeO2, and CeO2-ZrO2 promoted Ni-MgO catalysts were prepared via a facile coprecipitation method and applied to the CDR reaction. Among the prepared catalysts, the ZrO2-promoted Ni-MgO catalyst showed the highest methane conversion. The high catalytic performance of the ZrO2-promoted Ni-MgO catalyst is mainly due to easier reducibility, high Ni dispersion, and high specific surface area.

Promoting Effect of KIT‐6 to Support Ni‐Ce0.8Gd0.2O2‐δ as Efficient Coke‐Resistant Catalysts for Carbon Dioxide Reforming of Methane

A series of Ni‐Ce0.8Gd0.2O2‐δ/KIT‐6 composites with various mass ratios were prepared by the impregnation approach. TEM and XRD characterization results revealed that the KIT‐6 support improved the distribution of Ni‐Ce0.8Gd0.2O2‐δ nanoparticles through the confinement effect of ordered mesopores of KIT‐6. XPS measurement showed that the concentration of surface oxygen vacancies in Ni‐Ce0.8Gd0.2O2‐δ/KIT‐6 composite was higher than that in KIT‐6‐free Ni‐Ce0.8Gd0.2O2‐δ. The catalytic test toward CO2 reforming of CH4 indicated that the Ni‐Ce0.8Gd0.2O2‐δ/KIT‐6 exhibited higher catalytic activity and stability over 100 h at 700 °C than Ni‐Ce0.8Gd0.2O2‐δ. The enhanced performance was demonstrated to be due to improved nickel dispersion and higher concentration of oxygen vacancies in Ni‐Ce0.8Gd0.2O2‐δ/KIT‐6, which reinforced the catalytic activity and decoking ability in the reforming reaction, thus boosting the durability of the catalyst.

Studies of Ceria and Zirconia Promotion of Nickel Catalyst for Carbon Dioxide Reforming of Methane

The CO2 reforming reactions of methane were carried out using three types of Ni/δ-Al2O3s and the effects of the addition of CeO2 were examined. In this study, the addition of a high weight percentage of CeO2 focused on reducing the amount of deposited carbon. It was revealed that a high Al2O3 surface area was necessary for the effective reduction of the deposited carbon by the addition of 50% CeO2 with the lowest conversion decrease. The addition of CeO2 and ZrO2 (Ni/Al2O3(A)-CeO2(45)-ZrO2(5)) further decreased the deposited carbon to 0.14 mmol per 1 mol of produced CO at 1073 K.

Carbon dioxide reforming of methane over nickel catalysts supported on TiO2(001) nanosheets

As we all know, the critical problem of nickel catalysts for carbon dioxide reforming of methane is the deactivation of catalysts due to the carbon deposition and sintering of the active components under high temperature. It was reported that anatase TiO2 nanosheets with high-energy (001) facets had strong interaction with nickel, which was probably beneficial to resist sintering of nickel nanoparticles and to eliminate deposited carbon via oxygen migration. In this study, Ni nanoparticles were supported on TiO2 nanosheets with exposed high-energy (001) facets. The Ni/TiO2(001) catalysts were characterized by means of X-ray diffraction, transmission electron microscopy, physisorption of N2, X-ray photoelectron spectroscopy and H2 temperature-programmed reduction, and the spent catalysts were characterized by Roman and thermogravimetry analysis. The catalytic performance of Ni/TiO2(001) catalysts were measured for carbon dioxide reforming of methane reaction. It was found that the prepared Ni/TiO2(001) catalysts showed reasonably higher catalytic activity and stability compared with the nickel catalyst supported on commercial titanium oxide (P25). The high dispersion of nickel nanoparticles of Ni/TiO2(001) catalysts was helpful to the resistance towards carbon deposition and the strong metal-support interaction was helpful to the resistance towards nickel sintering on account of the unusual surface properties of TiO2(001).

Catalytic performance of N-doped activated carbon supported cobalt catalyst for carbon dioxide reforming of methane to synthesis gas

Abstract Activated carbon (AC) was treated with melamine to prepare nitrogen-doped carbon materials (AC-N), which used as support to prepare Co supported catalysts for CH4–CO2 reforming (DRM) reaction and its catalytic performance was investigated. The modified (Co/AC-N) and unmodified (Co/AC) catalyst were characterized by BET, H2-TPR, XRD, TEM, XPS, CO2-TPD and FTIR. It was found that the modified catalyst not only showed excellent stability, but also had better catalytic activity than the unmodified catalyst. Although the physical structure of modified catalysts is almost same with the unmodified catalysts, nitrogen and some oxygen functional groups such as pyridine nitrogen, pyrrole nitrogen, hydroxyl and oxygen incarbonyl groups were generated on the AC surface during the amination treatment. The generated surface nitrogen and oxygen functional groups affect not only influence the dispersion of active metals but affect the valence distributions of cobalt. Compared with the untreated catalyst, small active particle size with a narrow size distribution formed on the surface of N-doped catalyst. Moreover, the modified catalyst also provides more basic sites for the reforming reaction to accelerate the adsorption and dissociation of CO2 on the active site of the catalyst.

The Synthesis of Ce1 – xZr x O2 Oxides in Supercritical Alcohols and Catalysts for Carbon Dioxide Reforming of Methane on Their Basis

The effect of the features of starting zirconium compounds on the solvothermal synthesis of mixed Ce–Zr oxides in a flow reactor using ethanol and isopropanol as a supercritical medium was studied. The phase composition and structural properties of the synthesized samples were investigated using X-ray diffraction analysis (XRD) and Raman spectroscopy. The morphology and textural properties were studied by transmission electron microscopy (TEM) and thermal desorption of nitrogen. It was found that the use of zirconium oxychloride or acetate as the starting substances results in the formation of a mixture of phases enriched with cerium or zirconium, whereas the use of zirconium butoxide with acetylacetone as a complexing agent allows obtaining a homogeneous solid solution. The catalytic properties of the synthesized oxides with supported Ni were tested in methane dry reforming (MDR). The catalyst containing a single-phase oxide synthesized in the presence of acetylacetone exhibited much higher activity, selectivity and coking stability.

Intermetallides as the catalysts for carbon dioxide reforming of methane

Intermetallic catalysts for dry reforming of methane (DRM) based on Ni3Al with low content of Pt and Ru have been developed. Self-propagating high-temperature synthesis (SHS) was used as a method of catalyst synthesis. Ion implantation was used to change the physical, chemical and catalytic properties of Ni3Al as a matrix for this new type of catalysts for DRM. Ions of Pt and Ru were accelerated in an electrical field and impacted into a solid Ni3Al. The catalytic performances were evaluated between 600°C and 900°C at atmospheric pressure. The feed was CH4/CO2/He=20/20/60vol.% mixture. Particle size and chemical evolution of catalysts were studied by XRD (in situ and ex situ), SEM, EDS, HRTEM+EDS and XPS. The active components were shown to be primarily dispersed in the nearsurface layer of Ni3Al support as nanoparticles of size 5–10nm, which were distributed homogeneously or heterogeneously, depending on the catalyst composition. Spinel structure of some catalysts is resistant to carbonization and provides high catalyst stability in DRM. Modification of catalyst by ion implantation had several positive impacts: 1) high catalytic activity and stability in DRM, 2) reducing of carbon deposits, 3) Pt and Ru prevent Ni phase sintering by avoiding particle coalescence.

Dry reforming of methane over nano-Mo2C/Al2O3 catalyst: Effect of carburization conditions on excess carbon deposition

ABSTRACTIn this study, temperature-programmed carburization (TPC) has been used to prepare Mo2C/Al2O3 catalyst for carbon dioxide reforming of methane. Also, the effect of carburization conditions has been examined on excess carbon formation over the prepared catalysts. Minimum excess carbon of 0.51 wt% was obtained in a flow of 12.5 vol% CH4/H2 gas mixture, final carburization temperature of 750°C, and Mo loading of 12.5 wt%. This catalyst exhibited better initial activity due to lower excess carbon and higher carbide dispersion compared with other examined catalysts. However, the results of time on stream performance in the dry reforming of methane (DRM) revealed an increase in durability with an increase in Mo loading.

Facilely fabricating Mg, Ca modified Co based ordered mesoporous catalysts for CO2 reforming of CH4: The effects of basic modifiers

Co based catalysts have been widely investigated as the catalysts for carbon dioxide reforming of methane (CRM) reaction due to outstanding coke-resistant capacity. Herein, a series of Co based ordered mesoporous materials incorporated with Mg and Ca basic modifiers had been designed and fabricated by facile evaporation induced self-assembly (EISA) strategy. The obtained materials were systematically characterized by X-ray diffraction (XRD), N2 adsorption–desorption analysis, transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (H2-TPR), and CO2 temperature programmed desorption (CO2-TPD). The characterization results demonstrated that these materials calcined at 700 °C possessed relatively large surface areas (130.0–150.0 m2/g), big pore volume (0.30 cm3/g), narrow pore size distribution (9.5–11.0 nm), and uniform mesoporous channels. Due to these good textural properties and unobstructed mesoporous channels, these materials could accommodate the gaseous reactants with sufficiently accessible Co active sites, thus showing high catalytic activity toward CRM reaction. Besides, the Co active centers were in situ incorporated into and stabilized by the mesoporous framework. Therefore, the thermal agglomeration of the metallic Co nanoparticles during the CRM reaction could be effectively suppressed, displaying excellent catalytic stability. For the Mg and Ca basic modifiers, their incorporation greatly strengthened the surface basicity and intensified the chemisorption of CO2, which would be helpful in accelerating the surface coke elimination process. Therefore, these Co based ordered mesoporous materials incorporated with Mg and Ca basic modifiers could be considered as potential catalysts for CRM reaction.