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The utilization of carbon dioxide (CO 2 ) have been a lot of attention nowadays many researchers are trying to convert to methanol which has high demand in the terms of energy and chemical feedstock. The catalytic CO 2 hydrogenation was performed in continuous fixed-bed reactor. In this study, the influent of calcination temperatures over a series of copper-based catalyst with different promoted loading such as zinc, which prepared via impregnation methods supported on gamma-alumina were investigated. The characterization of the catalysts was studied using BET, TPR and XRD. The highest concentration of methanol converted from CO 2 was found at bimetallic copper-zinc catalyst with molar ratio of 1:1 and calcination temperature of 300 °C STY of 16.36 gkg Cat -1 h -1 with MeOH selectivity as 22.54%. [ABSTRACT FROM AUTHOR]

In this study, simultaneous production of hydrogen and carbon nanotubes from direct conversion of biogas is experimentally investigated. A series of monometallic Fe, Co, and Ni and bimetallic CoMo, NiMo, and FeMo supported on MgO was prepared and tested for catalytic conversion of biogas in a fixed-bed reactor at 900 °C and 1 atm. Among the monometallic catalysts, Co/MgO shows the highest production yields of H 2 and CNTs with excellent catalyst stability. Ni/MgO has a steadily deactivation with time on stream, while Fe/MgO exhibits the lowest catalytic performance due to the oxidation of iron species by CO 2 , resulting in a severe catalyst deactivation. For the bimetallic catalysts, the addition of Mo would greatly increase the production yields of H 2 and CNTs due to the higher metal dispersion and SMSI effects. NiMo/MgO can achieve a remarkable 100%CO 2 conversion, and 95%CH 4 conversion, producing gas products comprising of H 2 up to 74%v/v with H 2 /CO = 3.1. NiMo/MgO and CoMo/MgO catalysts provided the higher yields of H 2 and CNTs than FeMo/MgO catalyst, while FeMo/MgO produced the high graphitic CNTs due to the high solubility of carbon in Fe. The stability test under an extremely high GHSV of 600,000 ml/g-h reveals that NiMo/MgO shows the excellent stability. CoMo/MgO is rapidly deactivated due to a large carbon deposition, while FeMo/MgO still suffers from CO 2 oxidation, resulting in a severe deactivation. The long-term stability for 10 h confirms that NiMo/MgO can perform the excellent catalytic performance. The process shows a high potential for simultaneous production of H 2 and CNTs from abundant and renewable biogas. [Display omitted] • The direct catalytic conversion of biogas was investigated. • The addition of Mo to Fe, Co, and Ni improved the catalyst activity and stability. • The NiMo/MgO provided 100%CO 2 conversion and 95%CH 4 conversion. • The NiMo/MgO exhibited an excellent stability for 10 h. • The syngas with high hydrogen fraction of 74%v/v was obtained. [ABSTRACT FROM AUTHOR]

In this study, catalytic conversion of biogas into hydrogen and carbon nanotubes is investigated using an integrative process of dry reforming and methane decomposition. The catalytic improvement of cobalt catalysts promoted with various promoters: Mo, Ce, Zr, W, and Ca, is examined to discover the best combination that is resistant to a metal sintering. The addition of Mo shows an improved catalyst stability due to an enhanced metal-support interaction, avoiding metal sintering. The current process shows a remarkable CO 2 conversion of 99.4% and a high CH 4 conversion of 95.8%, while the gaseous products comprise of H 2 up to 77%v/v at 900 °C, GHSV of 4500 ml/g-h. The long-term stability test for 7 h shows that the catalysts promoted with Mo, Zr, and W could provide almost complete CO 2 conversion at 900 °C and under a high GHSV of 45,000 ml/g-h. The analysis of spent catalysts shows that deposited carbon composed of well-structured multi-walled carbon nanotubes (MWCNTs) with high graphitization (I G /I D = 2.14), compared to the commercial CNTs (I G /I D = 0.74). The as-synthesized CNTs could achieve 91%w/w purity without any purification. The process test at high temperature of 1000 °C, provides higher graphitization (I G /I D = 3.76) with compensation of lower yield of CNTs. This integrative process demonstrates a promising route to completely convert a renewable biogas into high-value products such as hydrogen and carbon nanotubes with less production of wastes. [Display omitted] • The integrative dry reforming and methane decomposition was proposed. • The addition of Mo greatly increased the catalyst activity and stability. • The H 2 -rich syngas with 98.6% purity and H 2 /CO ratio of 3.5 was produced. • The almost complete conversion of biogas was obtained. • The CNTs with 91%w/w purity was obtained. [ABSTRACT FROM AUTHOR]

We prepared Ni–Ce/Al-MCM-41 catalyst with enhanced activity at low temperatures via one-pot hydrothermal synthesis using kaolin as a silica precursor for CO 2 methanation and investigated the influence of Ce addition on the catalytic activity enhancement. The as-synthesized Al-MCM-41 possessed hexagonal mesoporous silica with a surface area of 436 m2/g and a mesopore of 3.8 nm, allowing the incorporation of Ni and Ce into the Al-MCM-41 structure. In a fixed-bed tubular reactor, the catalytic performance of the as-prepared catalyst was evaluated in terms of CO 2 conversion, CH 4 /CO selectivity, CH 4 yield, reaction rates per catalyst mass (r m), and catalyst surface (r s), TOF, activation energy, and the deactivation rates of its corresponding activities at 250–550 °C and 1 atm. As the Ce content increased, the catalytic activity greatly improved due to the improved Ni dispersion and higher CO 2 adsorption, although the porosity of the catalyst significantly decreased. With the optimum Ce content, 100% CH 4 yield was achieved at 350 °C and weight hourly space velocity (WHSV) = 20,000 mL g−1 h−1. The optimum catalyst also exhibited high stability with a deactivation rate of −0.072% Y CH4 g−1 h−1 over 76 h, attributed to the strong interaction between Ce and Al in Al-MCM-41. [Display omitted] • The MCM-41 could be prepared from natural kaolin. • The MCM-41 possessed high surface area of 436 m2/g and mesopore of 3.8 nm. • The optimum catalyst provided the CH 4 yield of 100% at 350 °C. • The optimum catalyst exhibited a high stability over 76 h. • The high stability of catalyst was attributed to the strong interaction between Ce and Al. [ABSTRACT FROM AUTHOR]

Effect of CoMo metal loading to MgO (1, 5, 30 and 50 wt%) on conversion of biogas by an integrative process was investigated at 900 °C under atmospheric pressure. The integrative process combines the direct methanation of CO 2 in biogas and the CH 4 decomposition to upgrade biogas to CH 4 and decompose to hydrogen and carbon nanotubes. Methane dissociative reaction is governed by the concentration of active metals on the catalyst surface, while DRM reaction is suppressed. The 30 wt%CoMo catalyst shows the optimal loading for production of high-purity H 2 (>90v/v%) and high yield of MWCNTs (2.33 gCNT/gCat-h) with 100%CO 2 conversion and 95%CH 4 conversion. Meanwhile, 1 wt%CoMo catalyst provided the single-walled CNTs with diameter of 2.5 nm, high surface area of 165 m2/g and high graphitization of I G /I D = 6.14. [Display omitted] • The 100%CO 2 conversion and 95%CH 4 conversion of biogas was obtained. • The hydrogen with 90%purity was produced from biogas. • The 30 wt%CoMo catalyst shows the optimum catalyst. • The high value-added MWCNTs was obtained. • The 1 wt%CoMo catalyst produced SWCNTs. [ABSTRACT FROM AUTHOR]

We introduced a novel combined process of CO 2 methanation (METH) and catalytic decomposition of methane (CDM) for simultaneous production of hydrogen (H 2) and carbon nanotubes (CNTs) from biogas. In this process, biogas is catalytically upgraded into CH 4 -rich gas in METH reactor using Ni/CeO 2 catalyst, and the obtained CH 4 -rich gas is subsequently decomposed into H 2 and CNTs in CDM reactor over CoMo/MgO catalyst. Among the three different process scenarios proposed, the combined process with a steam condenser equipped between METH and CDM reactors could greatly improve a CNTs productivity. The CNTs production yield increased by more than 2.5-fold, maximizing at 9.08 gCNTs/gCat with a CNTs purity of 90%. The deposited carbon product was characterized as multi-walled carbon nanotubes (MWCNTs) with a surface area of 136.0 m2/g, comparable with commercial CNTs of 199.8 m2/g. The remarkable I G /I D ratio of 2.18 confirms a superior portion of graphitic carbon in the synthesized CNTs upon the commercial CNTs with I G /I D = 0.74. Notably, the CH 4 conversion reached 94.5%, while the CO 2 conversion achieved 100%, resulting in the H 2 yield and H 2 purity higher than 90%. This combined process demonstrates a promising route for production of high quality CNTs and high purity H 2 with complete CO 2 conversion using biogas as abundant renewable energy resources. In addition, the test of raw biogas showed no deactivation of catalyst, justifying the implementation of the developed process for real biogas without purification. • The combined process could produce CNTs and H 2 with zero CO 2 emission. • The steam removal could greatly enhance the yield and quality of CNTs. • The synthesized CNTs has higher a graphitic carbon than the commercial CNTs. • The hydrogen purity was higher than 90%. • The CO 2 conversion could achieve 100%. [ABSTRACT FROM AUTHOR]

In this study, hydrogen and carbon nanotubes (CNTs) are simultaneously produced via a synergistic combined process of CO 2 methanation (METH) and chemical vapor deposition (CVD) processes using biogas as a feedstock. METH process could upgrade CO 2 containing biogas into CH 4 -rich gas which then decomposed into H 2 and forming CNTs over CoMo/MgO catalyst by CVD process. The effects of Ce addition to CoMo/MgO were investigated. Comprehensive characterization confirms that all as-synthesized samples composed of well-aligned multi-walled carbon nanotubes (MWCNTs) with a narrow size distribution. The Ce addition improved CoMo dispersion on MgO, resulting in smaller and uniform CNTs. The small addition of Ce into CoMo/MgO catalyst could enhance the production CNTs yield. The higher Ce addition would, however, result in the CNTs yield decreased, attributed to a high basicity of CeO 2 surface and a large coverage of CeO 2 on the catalyst surface. The I G /I D increased with increased Ce addition, while the surface area monotonically decreased, attributed to a decrease in defects of nanotubes. In addition, this wisely combined process could result in a remarkable 100%CO 2 elimination, while high CH 4 conversion of 90% was obtained. The H 2 production yield could gain more than 30 vol% with respect to H 2 in the feed stream. The H 2 yield and purity in the effluent gas stream were approximately 90%. • The combined process could provide a complete CO 2 elimination. • The small Ce addition could enhance both yield and quality of CNTs. • The obtained CNTs has a higher graphitic carbon than the commercial CNTs. • The CH 4 conversion could achieve more than 90%. • The additional H 2 production could gain more than 30%. [ABSTRACT FROM AUTHOR]

Low-cost CuFe catalysts with different calcination temperatures were synthesized by a facile citric acid complexation method. The formation of CuO and Fe 2 O 3 with minor CuFe 2 O 4 were observed after calcination at 600 °C and 700 °C, whereas the major phase of CuFe 2 O 4 spinel-type structure was detected at 800 °C. To elucidate the structural CuFe transformation with catalytic transfer hydrogenation (CTH), the calcined catalysts were activated in situ into active species using isopropanol as the hydrogen donor, and their catalytic performances were simultaneously employed for the CTH of furfural to furfuryl alcohol and 2-methylfuran. Interestingly, the metallic Cu with minor Cu 2 O and magnetite Fe 3 O 4 were generated after the CTH through combined XRD and ex situ XANES observations, acting as the active species for the reaction. The catalytic activity was higher for the CuFe600 and CuFe700 catalysts than for the CuFe800 catalyst because calcination at high temperature resulted in the formation of larger catalyst particles. Extended investigations on the catalyst lifetime confirmed that the deactivation of the CuFe700 catalyst was slower than that of the CuFe600 catalyst. Our investigation demonstrates the simultaneous catalyst activation and reaction accompanied by the catalyst recovery achieved by a magnetic field activated by isopropanol for the CuFe system. [Display omitted] • Isopropanol assisted CuFe activation and reaction via catalytic transfer hydrogenation. • Isopropanol activated CuFe exhibited superior performance over H 2 gas activation. • Ex situ XANES elucidated the structural CuFe transformation under isopropanol. • Metallic Cu and Fe 3 O 4 were generated by isopropanol without H 2 gas requirement. • Furfuryl alcohol and 2-methylfuran were generated from furfural hydrogenation. [ABSTRACT FROM AUTHOR]

Catalytic transformation of furfural to furfuryl alcohol and 2-methylfuran without H 2 supply toward transfer hydrogenation process using 2-propanol as a H 2 source was systematically investigated over the bimetallic NiCuAl and CoCuAl catalysts in comparison with the monometallic CuAl, NiAl, and CoAl catalysts. The XRD analysis confirmed the generation of Ni-Cu and Co-Cu alloys after the reduction in presence of H 2. The interaction between Cu and Ni or Co resulted in a simplicity of the reduction behavior of Ni and Co species observed in H 2 -TPR experiments. It was evident from pyridine adsorption FTIR analysis that the formation of bimetallic Ni-Cu and Co-Cu alloys apparently improved the stronger Lewis acidic sites. The influences of reaction temperature and time were examined and optimized to maximize the yields of furfuryl alcohol and 2-methylfuran. The highest two major products yield and selectivity with lower by-products were obtained over the NiCuAl and CoCuAl catalysts compared with the CuAl and NiAl catalysts. The superior performance of the bimetallic catalysts was attributed to the stronger Lewis acidic centre on the catalyst surface. The CoCuAl catalyst was found to have lower catalyst deactivation and carbon deposition among the CuAl and NiCuAl catalysts under H 2 -free atmosphere. Unlabelled Image • CTH of furfural over the supported NiCuAl and CoCuAl was investigated. • XRD confirmed the formation of Ni-Cu and Co-Cu alloys after reduction. • Addition of Ni and Co into the Cu species increased the stronger Lewis acidic sites. • The highest FOL and 2-MF yields were achieved over the NiCuAl and CoCuAl. • The CoCuAl showed lower catalyst deactivation and carbon deposition. [ABSTRACT FROM AUTHOR]