Catalytic Performance In Steam Reforming Research Articles

Highly Dispersed Nickel Nanoparticles on Hierarchically Ordered Macroporous Al2O3 and Its Catalytic Performance for Steam Reforming of 1-Methyl Naphthalene

In this study, we investigate the effect of a hierarchically ordered macroporous structure of alumina support on the steam reforming of 1-methyl naphthalene with mesoporous alumina-supported nickel and potassium (xK/Ni–MeAl), and macroporous alumina-supported nickel and potassium (xK/Ni–MaAl) catalysts. Hierarchically ordered macroporosity in Al2O3 supports plays an important role in maintaining the high Ni dispersion through multiple interactions in Ni–K over AlO4 tetrahedra in alumina. This, in turn, improves the catalytic performance of steam reforming, including high gas yields, turnover frequency for hydrogen production, and 1-methyl naphthalene conversion. At high K content, the Ni active sites over xK/Ni–MeAl catalysts significantly decrease, resulting in almost zero steam reforming rate in the reaction test. Conversely, the potassium–alumina interaction in xK/Ni–MaAl catalysts not only diminishes the formation of the inactive nickel aluminate phase but also maintains the highly dispersed Ni active sites, resulting in a high steam reforming rate.

Insight into the effect of CeO2 morphology on catalytic performance for steam reforming of glycerol

Shape-specific CeO2 nanocrystals (spheres, rods, cubes and nanoparticles) with well-defined crystal facets were successfully synthesized and used as the support to synthesize series Ni/CeO2. Ni/CeO2 was employed as the model catalysts to study the structure dependent behavior and reaction mechanism for hydrogen production from glycerol steam reforming (GSR). The metal-support interaction was finely tuned by altering the morphology of CeO2 support, which in turn affected the exposed specific surface area of nickel and oxygen vacancy concentration. The relationship between exposed surface area of active nickel as well as surface oxygen vacancies and catalytic performance was studied. Ni/CeO2-S with the mainly exposed (111) type planes obtained the strongest metal-support interaction. Electron effects due to the strong metal-support between nickel and cerium dioxide facilitated the formation of readily reducible nickel species (Niδ+). High nickel reduction and nickel dispersion contributed to the maximum active nickel exposure surface area, thus Ni/CeO2-S showed exceptional glycerol conversion. Meanwhile, the strong Ni-CeO2 interaction resulting in abundant oxygen vacancies that facilitated the dissociation of water to produce hydrogen, thus possessing a high H2 yield. Conversely, Ni/CeO2-NR and Ni/CeO2-NC have lower exposure areas and oxygen vacancy concentrations due to the different exposed crystal planes, and therefore have relatively poor catalytic activity. Moreover, the strong oxygen storage-release ability (CO-OSC-OSCC) promoted the oxidation of carbon deposition on Ni/CeO2-S. Additionally, carbon deposition was mainly the filamentous carbon growing towards the periphery, hence, Ni/CeO2-S obtained up to 25-h catalytic stability. The study of the regulatory role of Ni-CeO2 interaction on catalytic behavior can offer worthwhile direction for designing high-efficiency GSR catalysts.

Effect of the incorporation of reducibility promoters (Cu, Ce, Ag) in Co/ CaSBA ‐15 catalysts for acetic acid steam reforming

In this work, we have faced the problem associated with the addition of Ca to Co/SBA-15, which gave rise to an increase in the dispersion of the particles at the expense of increasing its reduction temperature, thus limiting its reducibility as demonstrated by XPS. This detrimental effect has been solved by the inclusion of reducibility promoters such as Cu, Ag and Ce. All these promoters led to an increase in the acetic acid conversion attributed to their beneficial effect in the catalyst reducibility. With the inclusion of Ce to Co/CaSBA-15, the high dispersion was maintained while the percentage of reduced Co species increased by ~90% compared with Co/CaSBA-15, leading to the best catalytic performance (X ~ 99%, YH2 = 71.8%) after 5 hours TOS in the acetic acid steam reforming (S/C = 2) at 600°C using a WHSV = 30.1 hours−1. Furthermore, Co-Ce/CaSBA-15 showed good stability with hydrogen yield close to the thermodynamic value. These results highlight the necessity of combining both dispersing additives and promoters of reducibility to enhance the catalytic performance in steam reforming.

A Review on Catalysts Development for Steam Reforming of Biodiesel Derived Glycerol; Promoters and Supports

In the last decades, environmental crises and increasing energy demand have motivated researchers to investigate the practical techniques for the production of clean fuels through renewable energy resources. It is essential to develop technologies to utilize glycerol as a byproduct derived from biodiesel. Glycerol is known as a sustainable and clean source of energy, which can be an alternative resource for the production of value-added chemicals and hydrogen. The hydrogen production via steam reforming (SR) of glycerol using Ni-based catalysts is one of the promising approaches for the entry of the hydrogen economy. The purpose of this review paper is to highlight the recent trends in hydrogen production over Ni-based catalysts using the SR of glycerol. The intrinsic ability of Ni to disperse easily over variable supports makes it a more viable active phase for the SR catalysts. The optimal reaction conditions have been indicated as 650–900 °C, 1 bar, and 15 wt% Ni in catalysts for high glycerol conversion. In this review paper, the effects of various supports, different promoters (K, Ca, Sr, Ce, La, Cr, Fe), and process conditions on the catalytic performance have been summarized and discussed to provide a better comparison for the future works. It was found that Ce, Mg, and La have a significant effect on catalytic performance as promoters. Moreover, SR of glycerol over hydrotalcite and perovskite-based catalysts have been reviewed as they suggest high catalytic performance in SR of glycerol with improved thermal stability and coke resistance. More specifically, the Ni/LaNi0.9Cu0.1O3 synthesized using perovskite-type supports has shown high glycerol conversion and sufficient hydrogen selectivity at low temperatures. On the other hand, hydrotalcite-like catalysts have shown higher catalytic stability due to high thermal stability and low coke formation. It is vital to notice that the primary concern is developing a high-performance catalyst to utilize crude glycerol efficiently.

Effect of boron doping and preparation method of Ni/Ce0.5Zr0.5O2 catalysts on the performance for steam reforming of ethanol

Ce0.5Zr0.5O2 supported Ni-based catalysts with a Ni loading of 10 wt% and a B loading of 0.5 wt% were prepared by co-precipitation (assigned as NiCeZr(C) and BNiCeZr(C), respectively) and impregnation (assigned as NiCeZr(I) and BNiCeZr(I), respectively) procedures to evaluate the effects of fabrication methods and B-doped on the catalytic performance for steam reforming of ethanol (SRE). These catalysts were characterized with XRD, TPR, TPO, TEM, BET, TG and EA. The well dispersed active species that can be obtained through co-precipitation and formation of a NiB alloy come from a B-doped catalyst, which can promote catalysis performance and reaction pathway. Further, it can improve the selectivity of hydrogen for a SRE reaction. Also, the B-doped catalysts possess a high oxygen storage capacity (OSC) via formation of CeBO3 under SRE ambience, which is the factor for removal of the carbonaceous species. TG and EA analyses demonstrate that there are fewer carbon deposits for the B-doped catalysts. The performance of the BNiCeZr(C) catalyst was preferential among these catalysts.

Hydrogen generation by steam reforming of tar model compounds using lanthanum modified Ni/sepiolite catalysts

The paper describes the preparation of Ni/xLa-SEP catalysts selected low-cost clay minerals as support that possess high catalytic performance for steam reforming of phenol-ethanol (SRPE) to sustainably produce hydrogen. The catalysts were characterized using inductively coupled plasma optical emission spectrometry (ICP-OES), N2 adsorption-desorption, X-ray diffraction (XRD), H2 pulse chemisorption, high-resolution transmission electron microscopy (HRTEM), hydrogen temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the addition of La reduced the active metal size and increased the active metal surface of the Ni/SEP catalyst. The Ni/10La-SEP catalyst exhibited the smallest active metal size (5 ± 0.5 nm) and highest active metal surface area (12.7 m2/gcat.). As expected, Ni/10La-SEP presented the highest carbon conversion and H2 yield (92.1 and 87.6%, respectively) during SRPE reactions. Moreover, the La addition enhanced the steam reforming (SR) of CH4 and water-gas shift (WGS) reactions and successfully suppressed the sintering and coking of the Ni/SEP catalyst.

Synthesis and characterization of Zr-promoted Ni-Co bimetallic catalyst supported OMC and investigation of its catalytic performance in steam reforming of ethanol

This article presents simple method for the OMC-6%Ni-6%Co (ordered mesoporous carbon containing Ni and Co metallic nanoparticles) catalyst synthesis with high surface area and more proper bimetallic nanoparticle dispersion; prepared successfully by soft template hydrothermal method and different zirconium loadings (0.5, 1, 2 wt %) accomplished by impregnation method, which was known as a desired method for the metal dispersion. The catalysts with/without promoter, were characterized by XRD, FTIR and N2 adsorption-desorption isotherms, FESEM, EDS, EDS mapping, HRTEM and TPR techniques and investigated in steam reforming of ethanol (SRE) at 250–400 °C. XRD and BET results indicated that zirconium addition more than 0.5% wt, decreased the average mesopore diameter of catalysts, total pore volume and particles size. Also, it was stated that Ni2+ and Co2+ were caught by the RF/F127 network and further reduced into metallic Ni and Co nanoparticles during the carbonization. The Ni and Co nanoparticles were well-dispersed in the OMC walls. FTIR spectroscopy revealed that F127 left the structure and formed the porous structure. TPR analysis of OMC-6%Ni-6%Co/2%Zr sample, indicated that the sample is reduced easily at low temperatures. FESEM and HRTEM images showed that carbon was precipitated in the CNT form on spent catalyst samples surfaces and confirmed the position of Ni and Co bimetallic nanoparticles on the CNTs tip in the OMC-6%Ni-6%Co/2%Zr sample. 2% Zr-promoted bimetallic catalyst revealed appropriate catalytic performance for SRE, such as high activity, hydrogen yield and proper stability due to the synergistic catalysis of cobalt and nickel. Also, effective factors, such as H2O/EtOH molar ratio and gas hourly space velocity (GHSV) were investigated on the OMC-6%Ni-6%Co/2%Zr catalyst sample.

A structured Cu-based/γ-Al2O3/Al plate-type catalyst for steam reforming of dimethyl ether: Self-activation behavior investigation and stability improvement

A plate-type anodic alumina supported Cu composition catalyst was developed to investigate its catalytic performance in steam reforming of dimethyl ether (DME). It is found that the fresh Cu/γ-Al2O3/Al catalyst without H2 pre-reduction treatment exhibited the similar catalytic activity as the pre-reduced one. The XPS results show that Cu+ species exist in the surface of the fresh catalyst, which results in the self-activation reaction. However, the Cu/γ-Al2O3/Al catalyst showed a quick deactivation at 350°C due to the sintering of copper. As an approach, a second component Ni was doped to the Cu-based catalyst, and a series of Cu/Ni/γ-Al2O3/Al catalysts with different Ni loadings were prepared by impregnation method. Furthermore, the effect of nickel loading and chemical state on the activity of catalyst was extensively investigated. The results show that the catalytic performance was related to both of the nickel loading and chemical state. The proper amount of nickel doping is helpful in improving the dispersion of copper species, and thus enhancing the catalytic activity. Finally, a 180h stability evaluation was carried out and the results show that the optimized Cu/Ni/γ-Al2O3/Al catalyst has an excellent stability under critical conditions with 400°C, and gives a 100% DME conversion, which demonstrated that the novel γ-Al2O3/Al monolith supported Cu and Ni composite catalyst was an excellent catalyst for steam reforming of dimethyl ether.

Steam reforming of dodecane and toluene over Ru/12SrO–7Al2O3 (S12A7) catalysts

Catalytic steam reforming of liquid fuels such as kerosene is an important route for hydrogen production for the fuel cells. However, there is serious catalyst deactivation due to the carbon deposition on the catalyst. In this study, in order to develop a catalyst that has superior catalytic performance for steam reforming of kerosene, 12SrO–7Al2O3 (S12A7) that can incorporate active oxygen ions into the nanocage, was paid attention as a support material, subsequently steam reforming of dodecane and toluene as kerosene model compounds was performed over various Ru/SrO–Al2O3 catalysts with S12A7 phase. The Ru/SrO–Al2O3 catalysts with high S12A7 content exhibited higher catalytic activity than a commercial Ru/Al2O3 catalyst, despite low Ru loading and Ru dispersion. The S12A7 content in the SrO–Al2O3 support was remarkably affected by the calcination conditions such as temperature, moisture, and cooling rate. The S12A7 content was the highest in the SrO–Al2O3 support calcined at 873K in a stream of moist nitrogen (pH2O: 1.9kPa). The turnover frequency (TOF) for steam reforming of dodecane over Ru/SrO–Al2O3 catalysts exponentially increased with an increase in the S12A7 content. This result indicates that the active oxygen species in S12A7 contribute to the acceleration of oxidation of CHx species on Ru metals.

Nano bimetallic alloy of Ni–Co obtained from LaCoxNi1−xO3 and its catalytic performance for steam reforming of ethanol

Bimetallic alloy nanoparticles of Ni–Co were obtained from reducing LaCoxNi1−xO3 and this method should be extended to prepare various bimetallic or polymetallic nanoparticles.

Elucidation of the roles of Re in steam reforming of glycerol over Pt–Re/C catalysts

In this paper, we report the fundamental surface properties of Pt/C and Pt–Re/C catalysts and their correlation with catalytic performance in steam reforming of glycerol. We found that the addition of Re increases the catalytic activity, H2/COx ratio, and CO2 selectivity. N2 physisorption, CO chemisorption, and attenuated total reflectance infrared (ATR-IR), Raman, and X-ray absorption spectroscopy (XAS) with in situ capabilities were employed to provide insight into the roles of Re. Using ATR-IR, we show that CO adsorption on reduced Pt–Re/C is stronger than on Pt/C. However, CO desorption from Pt–Re/C is much facilitated compared with that from Pt/C after steam pretreatment, which is more representative of the steam reforming conditions. In situ Raman and XAS studies suggest that oxidized rhenium species are formed in steam environments on the Pt–Re/C catalyst surface. The spillover of CO from neighboring Pt to such oxidized rhenium is likely the reason for the facile desorption of CO, which could further react to form CO2. Such facile CO desorption leads to enhanced glycerol steam reforming and water-gas shift activities over the Pt–Re/C catalyst.

Steam reforming of methanol over Cu/ZnO/ZrO2/Al2O3 catalyst

Abstract Steam reforming of methanol was investigated over Cu–ZnO–ZrO 2 –Al 2 O 3 catalysts at 473 and 573 K. The Cu:Zn:(Al + Zr) molar ratio was 3:3:4; however, the Zr:Al molar ratio was varied and the catalysts were pretreated at different calcination and reduction temperatures. The synthesized catalysts were characterized by N 2 physisorption, temperature-programmed reduction with H 2 (H 2 -TPR), X-ray diffraction, oxidized surface TPR, and infrared spectroscopy after carbon monoxide chemisorption. The crystalline size of Cu decreased on increasing the calcination temperatures from 573 to 623 K and increased on increasing the reduction temperatures from 523 to 573 K. Among the tested catalysts, the Cu–ZnO–ZrO 2 catalyst exhibited the highest and lowest hydrogen-formation rates at 473 and 573 K, respectively. After the reaction at 573 K, all the tested catalysts exhibited an increase in the Cu crystalline size, causing the catalyst deactivation. Among the tested catalysts, the Cu–ZnO–ZrO 2 –Al 2 O 3 catalyst, where the Cu:Zn:Al:Zr molar ratio was 3:3:2:2, showed the highest and most stable catalytic activity at 573 K. Cu dispersion and catalyst composition affected the catalytic performance for steam reforming of methanol.

Activation of Al–Cu–Fe quasicrystalline surface: fabrication of a fine nanocomposite layer with high catalytic performance

A fine layered nanocomposite with a total thickness of about 200 nm was formed on the surface of an Al63Cu25Fe12 quasicrystal (QC). The nanocomposite was found to exhibit high catalytic performance for steam reforming of methanol. The nanocomposite was formed by a self-assembly process, by leaching the Al–Cu–Fe QC using a 5 wt% Na2CO3 aqueous solution followed by calcination in air at 873 K. The quasiperiodic nature of theQC played an important role in the formation of such a structure. Its high catalytic activity originated from the presence of highly dispersed copper and iron species, which also suppressed the sintering of nanoparticles.

P-12 Preparation of Mo_2C catalyst and its catalytic performance for steam reforming of tar

P-12 Preparation of Mo_2C catalyst and its catalytic performance for steam reforming of tar

Promotional effect of Fe on perovskite LaNixFe1−xO3 catalyst for hydrogen production via steam reforming of toluene

The effect of Fe addition on catalytic activity and stability of LaNixFe1−xO3 perovskite catalyst was investigated for hydrogen production via steam reforming of tar using toluene as a model compound. The addition of Fe to LaNiO3 catalyst at the optimum amount enhanced the catalytic performance in steam reforming of toluene. LaNi0.8Fe0.2O3 catalyst shows the best performance in terms of catalytic activity and stability for 8 h of reaction time. The catalyst characterization indicates the presence of Ni-rich Ni–Fe smaller bimetallic particles, strong metal support interaction, and lower carbon deposition rate on LaNi0.8Fe0.2O3 catalyst. The synergy between Ni and Fe atoms on the small Ni–Fe bimetallic particles is crucial for high activity of the LaNi0.8Fe0.2O3 catalyst. In addition, the strong interaction between metal and support on the LaNi0.8Fe0.2O3 catalyst can prevent metal sintering, thus, achieving high catalytic stability.

Influence of the Urea Content in the Combustion Synthesis for Preparation of NiAl2O4 Support Catalytic to Steam Reforming of Methane

The aim of this work is to evaluate the catalytic performance in steam reforming of methane of the NiAl2O4catalysts prepared by combustion reaction with different urea levels. The catalysts were prepared with urea in the stoichiometric proportion, and with excess of 10% and 20%. The samples were characterized by DRX, textural analysis by nitrogen adsorption, SEM, TPR, and then, catalytically evaluated in the methane reforming reaction. The results showed the presence of NiAl2O4and traces of NiO for all the samples. The increase of the urea content caused an increase in the particle size and a reduction in the surface area, from 171 to 35 m2/g. All the samples presented irregular morphology. The TPR curves showed peaks of reduction of the NiO species, and reduction of nickel present in the NiAl2O4. Regarding the conversion of methane to synthesis gas, it was observed that the increase of the urea content allowed obtaining higher conversion. However, it was also observed a rapid deactivation of these catalysts due to high coke deposition on the active phases surfaces.

Catalytic steam reforming of biomass-derived tar for hydrogen production with K2CO3/NiO/γ-Al2O3 catalyst

A major problem of using Ni-based catalysts is deactivation during catalytic cracking and reforming, lowering catalytic performance of the catalysts. Modification of catalyst with alkali-loading was expected to help reduce coke formation, which is a cause of the deactivation. This paper investigated the effects of alkali-loading to aluminasupported Ni catalyst on catalytic performance in steam reforming of biomass-derived tar. Rice husk and K2CO3 were employed as the biomass feedstock and the alkali, respectively. The catalysts were prepared by a wet impregnation method with γ-Al2O3 as a support. A drop-tube fixed bed reactor was used to produce tar from biomass in a pyrolysis zone incorporated with a steam reforming zone. The result indicated that K2CO3/NiO/γ-Al2O3 is more efficient for steam reforming of tar released from rice husk than NiO/γ-Al2O3 in terms of carbon conversion and particularly hydrogen production. Effects of reaction temperature and steam concentration were examined. The optimum temperature was found to be approximately 1,073 K. An increase in steam concentration contributed to more tar reduction. In addition, the K2CO3-promoted NiO/γ-Al2O3 was found to have superior stability due to lower catalyst deactivation.

Synergism Between Constituents of Multicomponent Catalysts Designed for Ethanol Steam Reforming Using Partial Least Squares Regression and Artificial Neural Networks

Effects of different catalyst components on the catalytic performance in steam reforming of ethanol have been investigated by means of Artificial Neural Networks (ANNs) and Partial Least Square regression (PLSR). The data base consisted of ca. 400 items (catalysts with varied composition), which were obtained from a former catalyst optimization procedure. Marten's uncertainty (jackknife) test showed that simultaneous addition of Ni and Co has crucial effect on the hydrogen production. The catalyst containing both Ni and Co provided remarkable hydrogen production at 450°C. The addition of Ceas modifier to the bimetallic NiCo catalyst has high importance at lower temperatures: the hydrogen concentration is doubled at 350°C. Addition of Pt had only little effect on the product distribution. The outliers in the data set have been investigated by means of Hotelling T2 control chart. Compositions containing high amount of Cu or Ce have been identified as outliers, which points to the nonlinear effect of Cu and Ce on the catalytic performance. ANNs were used for analysis of the non-linear effects: an optimum was found with increasing amount of Cu and Ce in the catalyst composition. Hydrogen production can be improved by Ce only in the absence of Zn. Additionally, negative cross-effect was evidenced between Ni and Cu. The above relationships have been visualized in Holographic Maps, too. Although predictive ability of PLSR is somewhat worse than that of ANN, PLSR provided indirect evidence that ANNs were trained adequately.

Optimization of methanol steam reforming over a Au/CuO–CeO2 catalyst by statistically designed experiments

The catalytic performance for steam reforming of methanol over 5wt.% Au/CuO–CeO2 catalysts prepared by deposition–precipitation was investigated using a statistical set of experiments in order to optimize the methanol conversion with minimal carbon monoxide (CO) selectivity. The operating temperature, steam to methanol (S/M) ratio, liquid feed rate and the catalyst weight to He flow rate (W/F) ratio, were evaluated with a full 24 factorial design experimental matrix with four central points. The liquid feed rate displayed a much greater influence on the response, masking the importance of the other factors. At a fixed low liquid feed rate, only the operating temperature had a significant influence on the methanol conversion, whilst this plus the S/M ratio and their interaction influenced the CO selectivity. A central composite rotatable design was then used to approximate the optimal conditions by simultaneously considering the methanol conversion and CO selectivity. The optimum theoretical conditions were found to lie within an operating temperature of ~295°C to ~307°C and an S/M ratio of ~1.82 to 2.00 (at a liquid feed rate of 1cm3h−1 and a W/F ratio of 0.17gscm−3), in close agreement with the experimental results.

Microstructure of leached Al-Cu-Fe quasicrystal with high catalytic performance for steam reforming of methanol

The catalytic performance of steam reforming of methanol (SRM), cross-sectional microstructure and leaching process of an Al 63Cu 25Fe 12 quasicrystal (QC) catalyst were studied. The QC catalyst was prepared by the NaOH leaching. The leaching of the QC alloy generated a homogeneous leached layer composed of Cu, Fe, Al, and their oxides. The activity and stability of the QC catalyst for the SRM was much superior to those of related crystalline alloy catalysts, because the highly dispersed Fe species in the homogeneous leached layer of the QC catalyst enhances the catalytic activity and suppresses the aggregation of Cu particles. The quasiperiodic structure of the Al-Cu-Fe QC was stable against leaching and had a relatively low dissolution rate of Al among the Al-Cu-Fe alloys, which resulted in the formation of a homogeneous leached layer that was responsible for the high activity and stability for SRM.