RSC Advances
·
2018
·Vol. 8
·期 67
·38641-38647
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IF 2.936
Tianyu Guo,Xiaorong Nie,Jianping Du,Jinping Li
A series of Pd/CeO2-nanorods catalysts modified with alkaline-earth metals were prepared by the incipient impregnation method. Their catalytic properties in low-concentration methane oxidation were also investigated. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and H2-temperature-programmed reduction techniques. The catalytic results show that the Ca element doped in Pd/CeO2, with optimum molar ratio of Pd to Ca of 2 and calcination temperature of 450 °C, improved the properties of the Pd-based catalyst remarkably, which is attributed to strong Pd–support interaction and high oxygen mobility. Therefore, calcium is more suitable as a promoter for enhancing the activities of the Pd/CeO2 catalyst in methane oxidation.
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Nanoscale
·
2018
·Vol. 10
·期 47
·22348-22356
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IF 7.233
Xusheng Cheng,Dongxu Wang,Jiancong Liu,Xin Kang,Haijing Yan,Aiping Wu,Ying Gu,Chungui Tian,Honggang Fu
Decreasing Pd usage whilst maintaining a superior performance is promising, but remains a challenge in the catalytic field. Herein, we have demonstrated the highly efficient promotion of Mo2N with a reduced amount of Pd for the liquid-phase hydrogenation reaction. The Mo2N (2–3 nm) was uniformly anchored onto mesoporous SBA-15 by using PMo12 as the Mo source. The small size and good dispersion of Mo2N is favourable for allowing their effective contact with post-loading Pd. This good contact is conducive to developing a synergistic catalyst, which was verified by studying the liquid-phase hydrogenation of p-nitrophenol (PNP) to p-aminophenol (PAP) with NaBH4 as the H source. The conversion ability of PNP to PAP on 1 wt% Pd–Mo2N/SBA-15 was vastly superior to 1 wt% Pd/SBA-15 and even better than 20 wt% Pd/SBA-15. The low-Pd, highly efficient catalysis is ascribed to the transfer of the electrons from Mo2N to Pd for the easy activation of H. The synergy can be affected by the type of support used. SBA-15 is superior to SiO2 and the other supports, which could be related to the large surface area and the plentiful number of pores on SBA-15, which is favourable to the dispersion of Pd and Mo2N, and the transfer/diffusion of the reactants. In particular, a highly efficient catalyst can be achieved at an even more reduced Pd loading (0.05 wt%). The current method describes the design of a highly efficient catalyst for the hydrogenation reaction using low amounts of noble metals.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2019
·
IF 4.084
Fufeng Cai,Peijing Lu,Jessica Juweriah Ibrahim,Yu Fu,Jun Zhang,Yuhan Sun
Methanol steam reforming is regarded as a very promising process to generate H 2 suitable for fuel cells. Typically, the Pd-based catalysts can catalyze efficiently methanol steam reforming for hydrogen production . But their high selectivity to CO, a byproduct of methanol reforming reaction , severely limits their potential application. In this work, a series of Nb-modified Pd−Zr−Zn catalysts with different Nb loadings were prepared to study their catalytic activities with more focus on the role of Nb on Pd−Zr−Zn catalyst for methanol steam reforming. The prepared catalysts were fully analyzed by using various characterization techniques, for example, ICP , BET, SEM, XRD , H 2 -TPR, NH 3 -TPD, HRTEM , CO chemisorption , XPS, and Raman. The experimental results showed that an increase in Nb loading for the Nb-modified Pd−Zr−Zn catalysts led to a decrease of the methanol conversion and H 2 production rate. This was probably due to the decrease in the amount of oxygen vacancies on the catalyst surface . However, introduction of Nb into Pd−Zr−Zn catalyst increased the acid strength on the catalytic surface. The aldehyde species derived from methanol decomposition were readily transformed to HCOOH, thus yielding high selectivity to CO 2 for the Nb-modified Pd−Zr−Zn catalysts. Significantly, the addition of Nb to Pd−Zr−Zn catalyst facilitated the incorporation of Pd into the ZnO lattices, which led to the formation of Pd−Zn alloy. Consequently, the Nb-modified Pd−Zr−Zn catalysts exhibited significantly lower CO selectivity and production rate than the Pd−Zr−Zn catalyst. From the results, this work offers a new way to the rational design of selective methanol steam reforming catalysts to decrease the formation of byproduct CO.
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ChemCatChem
·
2019
·Vol. 11
·期 11
·2676-2682
·
IF 4.495
Qinglin Yuan,Wanbing Gong,Yixing Ye,Jun Liu,Yue Lin,Chun Chen,Haimin Zhang,Pengfei Li,Weiren Cheng,Xiangjun Wei,Changhao Liang
Graphical Coupling reaction : A novel Pd/BiOCl catalyst is designed to catalyze benzaldehyde for high-selectively synthesizing benzoin ethyl ether utilizing the nucleophilic action of Cl − ions. DFT calculations and experimental evidences demonstrated the key role of dissociated Cl − ions with Pd NPs by suppressing the dissociation of Cl − ions and changing the reaction pathway. Exploring novel catalyst supports with unique performance creates more opportunity for transforming organic chemicals in heterogeneous catalysis. In this paper, BiOCl is first presented as an effective support for Pd nanoparticles (NPs) toward application in the coupling reaction of benzaldehyde. The Cl − ion dissociates from BiOCl, which forms nucleophile with Pd nanoparticles; this is key for the one-step synthesis of benzoin ethyl ether, the conversion and selectivity of which can reach to 100 % and 97.9 % at 100 °C, respectively. DFT calculations reveal that Cl − ions can be stabilized by stronger Bi−Cl bonds through doping of Fe ions in substituting Bi sites in BiOCl. The parallel catalytic evaluation using Pd/Fe-doped BiOCl catalyst shows the suppression of coupling reaction, conversely, demonstrating the crucial role of nucleophile. This work provides new insights into support tailoring for the synthesis of vital organic chemicals in heterogeneous catalysis by changing chemical reaction pathway.
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Catalysis Science & Technology
·
2019
·Vol. 9
·期 5
·1238-1244
·
IF 5.726
Guohan Sun,Jiahuan An,Hong Hu,Changzhi Li,Songlin Zuo,Haian Xia
A green approach for the conversion of 5-(hydroxymethyl)furfural (HMF) to 5-methylfurfural (MF) by using size-controlled palladium catalysts has been developed. Palladium nanoparticles (Pd NPs) with various sizes supported on activated carbon were prepared with polyvinylpyrrolidone (PVP) as the capping agent. The reaction results showed that all the PVP-assisted Pd catalysts achieved high selectivity whilst the hydrogenation ability of Pd NPs could be rationally tuned by varying the mole ratio of Pd/PVP. 2.5% Pd–PVP/C (1 : 2) presented a satisfactory activity with 80% MF yield and 90% selectivity. The reaction kinetics study showed that the transformation of HMF into MF over bifunctional PVP-assisted Pd NPs underwent an acid-catalyzed esterification followed by a Pd-catalyzed hydrogenolysis procedure. The role of formic acid in the transformation is not only as a hydrogen-donating agent but also as a reactant to form the key intermediate. This work provides a novel and environmentally-friendly method for the selective hydrogenation of bio-based HMF to MF.
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CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Yuqi Geng,Jiaqi Li,Wenjuan Lu,Ning Wang,Zeyang Xiang,Yanzhao Yang
In this paper, superparamagnetic Fe 3 O 4 @SiO 2 -NH 2 nanoparticles were applied to adsorb Au(III)/Pd(II)/Pt(IV) in HCl medium. The successful synthesis of Fe 3 O 4 @SiO 2 -NH 2 was characterized through TEM, SEM and FT-IR. Electrostatic interaction between magnetic NPs and metal anions was proposed as the main adsorption mechanism by zeta potential analysis. Maximum adsorption capacities and adsorption behaviors under metal anions concentrations, acidity, NaCl, kinetic and isotherm models were investigated. Notably, the Fe 3 O 4 @SiO 2 -NH 2 shows the excellent acidity and salinity resistance on Au(III), Pd(II) adsorption. The separation routine among Au(III), Pd(II) and Pt(IV) was proposed. As investigated, Pt(IV) could be isolated due to the less adsorption amount onto Fe 3 O 4 @SiO 2 -NH 2 (≤1%). Then, the adsorbed Au(III) was eluted selectively by HCl + N-hexanol alcohol + ethanol + H 2 O 2 mixing solution. Then, the adsorbed Pd(II) was completely eluted by thiourea solution. The recovery efficiencies of Au(III), Pd(II) and Pt(IV) were kept over 92%, 97% and 94% respectively, during 5 turns of cycling separation experiments. Total loss amount of Fe is around 7%. Hence that, the particle demonstrates the good stability and high adsorption capacity, which possess great potential for practical Au(III), Pd(II) and Pt(IV) separation.
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FUEL
·
2018
·
IF 4.908
Lei Yue,Jiamao Li,Chao Chen,Xiaolong Fu,Yu gong,Xiulong Xia,Jingwei Hou,Chengjian Xiao,Xiaojun Chen,Linjie Zhao,Guangming Ran,Heyi Wang
Dry reforming of methane (DRM) reaction is an environment-friendly process to convert greenhouse gases, methane (CH 4 ) and carbon dioxide (CO 2 ) into synthesis gases for industrial application. However, the catalysts used for DRM reaction always deactivate at high temperatures due to the sintering of metal nanoparticles and coking on the active surface. Core-shell structures composed of metal cores surrounded by oxide shells (core-shell structures) have been confirmed to be thermal-stable by solving the two problems. Pd@SiO 2 core-shell nanocatalyst has been prepared by using a sol-gel process, along with two supported catalysts prepared by using impregnation method in this work. The catalysts were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), N 2 adsorption-desorption isotherms, CO chemisorption, inductively coupled plasma optical emission spectrometry (ICP-OES). The Pd@SiO 2 after thermal treatment at 700 °C for 6 h exhibits no obvious sintering. For DRM reaction catalyzed by Pd@SiO 2 core-shell nanocatalyst, the conversions of CO 2 and CH 4 are 89% and 83% respectively, which show no significant decrease for >10 h. However, two supported Pd catalysts (Pd cub/SiO 2 and Pd/SiO 2 ) deactivate to a very low activity (conversion lower than 20%). The results suggest that the Pd@SiO 2 nanocatalyst is excellent for DRM reaction, which also can be used for other heterogeneous catalysis reaction at high temperatures.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2018
·
IF 3.235
Jing Zheng,Min Zhang,Yang Ling,Jingli Xu,Shunzhong Hu,Tasawar Hayat,Njud S. Alharbi,Fan Yang
In this paper, multifunctional nanotubes were prepared by directly combing iron oxide (Fe 3 O 4 ) nanoparticle(NPs) decorated carbon nanotubes (CNTs), and palladium (Pd) NPs together with polypyrrole (PPy) in a facile way. Firstly, magnetic CNT composite (CNTs/Fe 3 O 4 ) was synthesized by the high temperature decomposition process, then PPy could be easily immobilized on the magnetic CNTs. Furthermore, Pd NPs were accumulated on the surface of CNTs/Fe 3 O 4 @PPy to obtain one dimensional CNTs/Fe 3 O 4 @PPy/Pd composite. The composite extraordinary amplified the electrochemical response, providing a highly sensitive electrochemical platform for triclosan detection. This electrochemical sensors had the advantage of fast response, cheap instrument, low cost, simple operation, high sensitivity and real-time detection in situ condition. Moreover, the sensor exhibited a wide linear response range for triclosan (2.247 × 10 −9 M to 2.752 × 10 −7 M) with a detection limit of 1.417 × 10 −9 M, respectively. In addition, the electrochemical sensor reported herein was applied for the detection of triclosan in real samples, revealing promising applications in developing the sensor for environmental inspection and monitoring.
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ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
·
2018
·
IF 3.974
Yuan Chen,Yuancai Chen,Jingyi Wu,Jianyi Zhang
In this paper, we found a bacteria ( Bacillus wiedmannii MSM) that could not only culture quickly under aerobic condition , but also can biological reduction of Pd (II) under both aerobic and anaerobic conditions. For reducing Pd (II) by Bacillus wiedmannii MSM, the best electron donor was sodium formate and the best growth time was 24 h (mid-log growth phase cells). TEM indicated that a lot of palladium nanoparticles (Pd-NPs) were mainly located in the periplasmic space of the live cells. However, the autoclaved cells could not synthesize Pd-NPs, which proved the role of enzyme in the reduction of Pd (II). A few of Pd-NPs were only formed on the surface of Cu 2+ -treated cells, which proved the main but not the only role of periplasmic hydrogenase in the reduction of Pd (II). XRD and XPS also proved that Pd-NPs could be synthesized by live cells over broad ranges of temperature (20–40 °C) and pH (pH 3.0–7.0). This may be especially useful for in situ reduction and remediation of Pd (II) for both anaerobic and aerobic wastewater.
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Journal of Materials Chemistry A
·
2017
·Vol. 6
·期 5
·2264-2272
·
IF 8.867
Jing Li,Hu Zhou,Han Zhuo,Zhongzhe Wei,Guilin Zhuang,Xing Zhong,Shengwei Deng,Xiaonian Li,Jianguo Wang
The key bottleneck of applying Pd catalysts in fuel cells is their low activity and poor stability during the oxygen reduction reaction (ORR) although less precious Pd is still a promising alternative to Pt. Hence, new strategies to improve the performance of Pd in the ORR need to be developed. In this study, supported Pd (3.6 nm in average) catalysts on TiO2 with and without oxygen vacancies (VO) have been prepared via facile pyrolysis. Compared with commercial Pt/C (20 wt%) and Pd/TiO2 catalysts, Pd/TiO2-VO (10 wt%) demonstrated superior oxygen reduction activity, better durability, and higher methanol tolerance capability in alkaline solution. By means of experimental characterizations (ESR and XPS) and density functional theory (DFT) calculations, electron transfer from TiO2-VO to Pd nanoparticles (NPs) led to an electron-rich Pd surface and strong metal–support interactions (SMSIs). The electron-rich Pd NPs enhanced the adsorptions of key intermediates, lowered the Gibbs free energy of the ORR, and improved the ORR activity. SMSIs between Pd NPs and TiO2-VO endowed the catalyst with excellent stability and immunity to methanol poisoning. Therefore, the electron transfer from TiO2-VO to Pd NPs plays a crucial role in promoting the ORR performance of Pd-based electrocatalysts, which may be a new strategy to design high-performance ORR catalysts.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2017
·
IF 4.233
Ziying Wang,Tong Zhang,Chen Zhao,Tianyi Han,Teng Fei,Sen Liu,Geyu Lu
In this paper, we demonstrate room-temperature NO 2 gas sensors using Pd nanoparticles (NPs) and SnO 2 NPs decorated reduced graphene oxide (Pd-SnO 2 -RGO) hybrids as sensing materials. It is found that ultrafine Pd NPs and SnO 2 NPs with particle sizes of 3–5 nm are attached to RGO nanosheets . Compared to SnO 2 -RGO hybrids, the sensor based on Pd-SnO 2 -RGO hybrids exhibited higher sensitivity at room temperature , where the response to 1 ppm NO 2 was 3.92 with the response time and recovery time being 13 s and 105 s. Moreover, such sensor exhibited excellent selectivity , and low detection limit (50 ppb). In addition to high transport capability of RGO as well as excellent NO 2 adsorption ability derived from ultrafine SnO 2 NPs and Pd NPs, the superior sensing performances of the hybrids were attributed to the synergetic effect of Pd NPs, SnO 2 NPs and RGO. Particularly, the excellent sensing performances were related to high conductivity and catalytic activity of Pd NPs. Finally, the sensing mechanism for NO 2 sensing and the reason for enhanced sensing performances by introduction of Pd NPs are also discussed.
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CRYSTENGCOMM
·
2017
·Vol. 19
·期 37
·5686-5691
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IF 3.474
Zhao Huang,Kai Cai,Huan Zhang,Zilan Hong,Zhaodong Yuan,Heyou Han
A facile method for the synthesis of Au-pearl/Pd-wire heterostructured nanonecklaces (APHNs) was developed for the first time, in which regular Au pearls with controllable size and interval distance were interlinked into a string by an ultrathin and ultralong Pd nanowire. The distribution density of Au nanopearls was regulated by the concentration of the reducing agent, while their size was controlled by the amount of the Au precursor. In the study of degradation of 4-nitrophenol (4-NP), the catalytic properties of several typical APHNs are proved to be inherently related to their morphology. By comparison with other nanostructures and commercial Pd/C, the APHNs show superior catalytic activities and better stability in general. The study demonstrated that novel heterostructures have superior catalytic properties in the degradation of 4-NP. Moreover, the nanostructures have the potential to be used as a high-efficiency catalyst in other catalytic reactions.
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