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•Effective deoxygenation of palm oil to green diesel over supported metal catalysts.•The order of catalytic activity is Co>Pd>Pt>Ni catalysts.•DCO is selective over Ni, Pd, and Pt, ...while DCO, DCO2, HDO are all selective over Co.•Turnover frequency (TOF) over monometallic species supported on γ-Al2O3.•Reaction network in hydrotreating of palm oil based on a model-compound study.
Diesel-like alkanes, so-called green diesel, produced from vegetable oil, have emerged as an important biofuel to replace petroleum diesel. In the present work, the deoxygenation of palm oil to green diesel was performed in a trickle-bed reactor over four γ-Al2O3-supported monometallic catalysts (Co, Ni, Pd, and Pt). The catalysts with various metal loadings (2–10wt.%) were prepared by the incipient wetness impregnation method and were characterized by XRD, TPR, N2 sorption, TEM, and CO pulse chemisorption. The results revealed that metallic sites of the catalysts were formed after pre-reduction in H2 with differences in metal particle size and metal dispersion on γ-Al2O3. The reaction tests revealed that the catalytic activity was in the order of Co>Pd>Pt>Ni, whereas the turnover frequency (TOF) increased with increments of the metal particle size. The decarbonylation reaction was more dominant than the hydrodeoxygenation reaction when the reaction was catalyzed by Ni, Pd, and Pt catalysts. Meanwhile, the contribution of decarbonylation and/or decarboxylation was nearly comparable to that of the hydrodeoxygenation reaction over Co catalyst. By combining the reaction tests with a model compound, oleic acid, a reaction network for the deoxygenation of palm oil was suggested and discussed.
Increasing concerns on global warming and climate change have led to numerous attempts and advanced technology developments to tackle the problem of excessive greenhouse gases emitted to the ...atmosphere. One of the technical strategies receiving great attention is the application of membrane technology for greenhouse gas separation/capture. Such technology exhibits significant advantages over other conventional methods in terms of removal efficiency, compactness, and environmental friendliness. Many state‐of‐the‐art membrane developments as well as its applications to post‐combustion treatment, which could be a promising approach for reducing CO2 emission from point sources, are thoroughly reviewed. Furthermore, a comprehensive survey on the future perspective of membrane technologies as a potential solution for CO2 removal and utilization is provided.
The state‐of‐the art membrane developments, especially for CO2 separation via the two membrane technologies, namely, membrane gas separation and membrane contactor, are updated. Concepts, challenges, and strategies to tackle the limitations of both membrane technologies are discussed. Future perspectives of these technologies as a potential solution for CO2 removal and utilization are discussed.
The catalyst with an optimum composition of Cu:Zn:Zr (38.2:28.6:33.2) exhibited a homogeneous dispersion of metal components, and achieved the highest methanol yield. Display omitted
•A series of ...CuO–ZnO–ZrO2 catalysts with different metal compositions were prepared.•Binary CuO–ZrO2 catalyst exhibited higher methanol selectivity.•Increasing Zn/Cu ratios provided a better inter-dispersion of metal components.•The optimum catalyst composition of Cu–Zn–Zr (CZZ-4) was 38.2:28.6:33.2.•The CZZ-4 achieved the highest methanol yield (219.7gCH3OHkgcat−1h−1) at 240°C.
CO2 hydrogenation was carried out over a series of CuO–ZnO–ZrO2 catalysts prepared via a reverse co-precipitation method. The influence of catalyst compositions on the physicochemical properties of the catalysts as well as their catalytic performance was investigated. The catalysts were characterized by means of N2-sorption, X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), scanning electron microscopy (SEM), H2-temperature programmed reduction (H2-TPR), H2 and CO2 temperature-programmed desorption (H2- and CO2-TPD). The binary CuO–ZrO2 (67:33) catalyst exhibits the highest methanol selectivity at all reaction temperature and its maximum yield of methanol (144.5gmethanolkgcat−1h−1) is achieved at 280°C, owing to the strong basic sites and the largest CuO crystallite size. The addition of Zn to the binary CuO–ZrO2 catalyst causes a higher Cu dispersion and an increased number of active sites for CO2 and H2 adsorption. However, the basic strength of the ternary CuO–ZnO–ZrO2 catalysts is lower than the binary CuO–ZrO2 catalyst which provides the maximum yield of methanol at lower reaction tempertures (240 and 250°C), depending on the catalyst compositions. The optimum catalyst composition of Cu–Zn–Zr (38.2:28.6:33.2) gives a superior methanol productivity of 219.7gmethanolkgcat−1h−1 at 240°C. The results demonstrate the possibility of controlling catalytic CO2 hydrogenation via tuning the catalyst composition.
Lignocellulosic biomass; hemicellulose, has been recognized as one of the most important renewable bioresources for production of alternative biofuels and biochemicals. The successful utilization of ...biomass derived from agricultural feedstocks to replace petroleum and petrochemical products would strongly support the sustainable bio-economy and biorefinery industry around the world. C5 and C6 sugars produced by the deconstruction of lignocellulosic materials through hydrolysis processes can be further converted to key intermediate chemicals, including furfural, 5-hydroxymethylfurfural, furan and organic acids. Among these, furfural is considered as a promising biomass-derived platform which can be a key intermediate for producing a variety of C4 and C5 species, such as, furan, tetrahydrofuran, pentanediol, lactic acid, and levulinic acid. This review will show the catalytic processes, especially, heterogeneous catalysis, for converting furfural into value-added biochemicals and biofuels. The applications of these compounds are added as background information, and the research trends based on several publications and patents in the past decade are intensively analyzed.
•This review showed the catalytic process for biofuel and biochemical production.•Overview concept of lignocellulosic biomass utilization was demonstrated.•Furfural, biomass-derived platform, to value-added C4 and C5 chemicals was focused.
The deoxygenation of waste chicken fat containing a high degree of free fatty acids (FFAs) and water has been implemented to produce a green diesel, known as biohydrogenated diesel (BHD). The effect ...of the water and free fatty acid content in the chicken fat on the conversion, BHD yield, and liquid/gas product distribution was investigated over a Ni/γ-Al2O3 catalyst in a trickle-bed reactor. The major reaction pathway was decarbonylation/decarboxylation (DCO/DCO2), whereas hydrodeoxygenation was minor. Methane from methanation of the resultant CO/CO2 and propane cracking was a major gaseous product. The FFA and water content improved the BHD yield and the overall contribution of the DCO/DCO2. The presence of water accelerated the breakdown of the triglyceride molecules into FFAs. Therefore, waste chicken fat from food industries containing a high degree of FFAs and water content can be used as a low-cost feedstock for renewable diesel production without requirement of a pretreatment process.
5-Hydroxymethylfurfural (HMF) derived from cellulosic sugars has become increasingly important as a platform chemical for the biorefinery industry because of its versatility in the conversion to ...other chemicals. Although HMF can be produced in high yield from fructose dehydration, fructose is rather expensive because it requires multiple processing steps. On the other hand, HMF can be produced directly from highly abundant glucose, which could reduce time and cost. However, an effective and multifunctional catalyst is needed to selectively promote the glucose-to-HMF reaction. In this work, we report a bifunctional phosphated titanium dioxide as an efficient catalyst for such a reaction. The best catalyst exhibits excellent catalytic performance for the glucose conversion to HMF with 72% yield and 83% selectivity in the biphasic system. We achieve this by tuning the solvent system, controlling the amount of Brønsted and Lewis acid sites on the catalyst, and modification of the reaction setup. From the analysis of acid sites, we found that the addition of phosphate group (Brønsted acid site) onto the surface of TiO
2
(Lewis acid site) significantly enhanced the HMF yield and selectivity when the optimum ratio of Brønsted and Lewis acid sites is reached. The high catalytic activity, good reusability, and simple preparation method of the catalyst show a promise for the potential use of this catalytic system on an industrial scale.
Tunable Lewis and Brønsted acid sites on P-TiO
2
tandem catalysts for glucose-to-HMF conversion providing high HMF yield (72%) and selectivity (83%).
•Novel composite catalysts of Ni-CNTs over mesocellular silica were synthesized.•A great improvement of catalyst stability in dry reforming reaction was reported.•Selective formation of carbon ...products as tube length extension of CNTs was found.
In this research, the novel composite catalysts between nickel and carbon nanotubes (CNTs) over mesocellular silica (MS) support were synthesized with an attempt to improve their stability to deactivation due to coke deposition in dry reforming reaction. Accordingly, the MS support was primarily prepared based on the synthesis of SBA-15 mesoporous silica with 1,3,5-trimethylbenzene (TMB) as a pore expanding agent. After that, nickel metal was loaded onto the MS support by using an incipient-wetness impregnation method, followed by CNTs synthesis via catalytic chemical vapor deposition (CCVD) technique through tip-growth mechanism. It was found that the existence of CNTs composite catalysts with nickel metal clusters on the tips of CNTs (Ni-CNTs/MS catalysts) could significantly improve the catalyst stability in dry reforming reaction (at 650°C for 24h) and simultaneously inhibit reverse water–gas shift reaction compared to that of Ni/MS catalyst. After 24h time on stream, CO2 and CH4 conversions of Ni/MS catalyst were approximately decreased by 10%, while those of Ni-CNTs/MS catalyst were increased by 3%. This outstanding performance could be attributed to selective formation of carbon by-products as the tube-length extension of the existing CNTs. Accordingly, the active surface of Ni-CNTs/MS catalysts were remained constant throughout the period of dry reforming reaction.
Oil palm male flowers (PMFs), an abundant agricultural waste from oil palm plantation in Thailand, have been utilized as an alternative precursor to develop nanoporous carbons (NPCs) via ...microwave-assisted pyrolysis combined potassium hydroxide (KOH) activation. The influences of relevant processing variables, such as activating agent ratio, microwave power, and activation time on the specific pore characteristics, surface morphology, and surface chemistry of PMFs derived nanoporous carbons (PMFCs) have been investigated to explore the optimum preparation condition. The optimum condition under a microwave radiation power of 700 W, activation holding time of 6 min, and activating agent ratio of 2:1 obtained the PMFC with the highest Brunauer–Emmett–Teller (BET) surface area and total pore volume approximately of 991 m2/g and 0.49 cm3/g, composed of a carbon content of 74.56%. Meanwhile, PMFCs have a highly microporous structure of about 71.12%. Moreover, activating agent ratio and microwave radiation power indicated a significant influence on the surface characteristics of PMFCs. This study revealed the potential of oil palm male flowers for the NPCs’ production via microwave-assisted KOH activation with a short operating-time condition.
Abstract
Glycerol is a low-cost byproduct of the biodiesel manufacturing process, which can be used to synthesize various value-added chemicals. Among them, 1,2-propanediol (1,2-PDO) is of great ...interest because it can be used as an intermediate and additive in many applications. This work investigated the hydrogenolysis of glycerol to 1,2-PDO over Co–Cu bimetallic catalysts supported on TiO
2
(denoted as CoCu/TiO
2
) in aqueous media. The catalysts were prepared using the co-impregnation method and their physicochemical properties were characterized using several techniques. The addition of appropriate Cu increased the glycerol conversion and the 1,2-PDO yield. The highest 1,2-PDO yield was achieved over a 15Co0.5Cu/TiO
2
catalyst at 69.5% (glycerol conversion of 95.2% and 1,2-PDO selectivity of 73.0%). In the study on the effects of operating conditions, increasing the reaction temperature, initial pressure, and reaction time increased the glycerol conversion but decreased the selectivity to 1,2-PDO due to the degradation of formed 1,2-PDO to lower alcohols (1-propanol and 2-propanol). The reaction conditions to obtain the maximum 1,2-PDO yield were a catalyst-to-glycerol ratio of 0.028, a reaction temperature of 250 °C, an initial H
2
pressure of 4 MPa, and a reaction time of 4 h.
Being able to balance between high catalytic activity and good stability under elevated reaction temperature is a great challenge for dry reforming of methane over nickel-based catalysts. In this ...work, two strategies including bimetallic formation and metal restriction over defects of hexagon boron nitride are combined. The integration of urea-based exfoliation technique with a consecutive solution combustion method employing urea as fuel is demonstrated over boron nitride supported catalysts. Anchoring of NiCo alloy onto defective hexagonal boron nitride nanosheet could enhance carbon removal significantly. The defective h-BN support with its promising basicity improves CO2 adsorption on catalysts’ surface, hence facilitates elimination of inactive carbon species. As a result, the catalyst exhibits high catalytic activity with 83.9% and 90.3% conversion for CH4 and CO2, respectively, and keep 100% retention during 130 h of reaction time at 750 °C. This work provides an alternative to develop high-performance catalysts for dry reforming of methane.
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•NiCo catalysts over defective boron nitride nanosheets were prepared.•Boron nitride nanosheets facilitated highly dispersed bimetallic site formation.•Cooperation of Co could enhance tolerance towards carbon formation of Ni.•NiCo catalysts over boron nitride for dry reforming of methane were demonstrated.
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