CHEMICAL ENGINEERING SCIENCE
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2023
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IF 4.7
Shidong Wang,Yaxi Wang,Xinru Wu,Cejun Hu,Hongwei Zhang,Qinyang Cui,Xiaojun Bao,Pei Yuan
Pore diffusion effect plays a crucial role in heterogeneous hydrogenation of unsaturated polymers. However, how large pore size can eliminate the pore diffusion limitation remains a controversial issue. Herein, we prepared a series of Pd/SiO 2 catalysts with graded pore sizes and investigated the effect of pore size on hydrogenation activity of nitrile butadiene rubber (NBR). It is found that when the catalyst pore size (D cat ) is 7 times of the diameter of NBR chains (D NBR ), the Weisz modulus Φ can be reduced to < 0.3 thus the internal mass transfer limitation can be eliminated, making NBR easier to approach the active sites. Consequently, the catalysts with the D cat /D NBR > 7 exhibit excellent catalytic activity (96.7%) and selectivity (100%) to C = C. This work emphasizes that the pore size of catalysts can regulate the pore transfer limitation and the accessibility of internal active sites, providing useful guidance for the design of efficient macromolecular hydrogenation catalysts.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2023
·
IF 22.1
Tian-Wen Jiang,Xianxian Qin,Ke Ye,Wei-Yi Zhang,Hong Li,Wenhui Liu,Shengjuan Huo,Xia-Guang Zhang,Kun Jiang,Wen-Bin Cai
Electrochemical CO 2 reduction reaction to formate (CO 2 RRTF) on Pd-based surfaces merits very low overpotentials, yet is challenged with identification of a high-performance catalyst and validation of the reaction pathway. In this work, an interactive study of catalyst and mechanism is presented to address the above bottleneck. On one hand, inspired by preliminary mechanistic understanding of HCOOH ↔ CO 2 interconversion at Pd surfaces, a Bi-modified Pd/C with the known high performance towards formic acid dehydrogenation (FAD) is elected as the prototype candidate catalyst for CO 2 RRTF, exhibiting indeed significantly higher activity, selectivity, durability and extended working potentials. On the other hand, the CO 2 chemical hydrogenation mechanism is clarified with monodentate formate being the key intermediate for CO 2 RRTF on Pd surfaces, by applying isotope labeled ATR-SEIRAS measurement and kinetic analysis in conjunction with DFT calculations. The research paradigm facilitates locating efficient catalysts and advancing mechanistic study for CO 2 RRTF on Pd surfaces and beyond.
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RENEWABLE ENERGY
·
2023
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IF 8.7
Qunying Sun,Huanhuan Zhang,Yanping Fan,Linyan Bian,Qiuming Peng,Baozhong Liu
Regulating the electronic structure of noble metals through metal alloy–support interactions is significant for hydrogen economy . Herein, a PdAg alloy highly dispersed on the surface of Ti 3 C 2 is successfully designed through a simple microwave-assisted reduction method. The catalytic activity of PdAg alloys with various molar ratios manifests obviously enhanced catalytic activity compared to monometallic catalysts toward hydrogen generation in ammonia borane (AB) hydrolysis. Specifically, Pd 4 Ag 1 /Ti 3 C 2 presents an optimal turnover frequency (TOF) value of 1296 min− 1 at room temperature and a lower activation energy ( E a ) of 38.8 kJ mol -1 . Through the experimental results, the formation of a PdAg alloy with the introduction of the second metal Ag adjusts the electronic structure around Pd and enhances the catalytic activity. Additionally, the metal alloy–support interaction between Ti 3 C 2 and the PdAg alloy significantly promotes hydrogen generation during the hydrolysis of AB. This study provides new ideas and a reasonable basis for heterogeneous catalysis based on bimetallic catalysts .
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2022
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IF 7.139
Wenxin Liu,Jiabin Zou,Shuni Li,Jinkun Li,Feihu Li,Zili Zhan,Yeguang Zhang
Hydrogen sensors are easily deactivated by hexamethyldisiloxane (HMDSO) poisoning. Moreover, the existing anti-poisoning strategies can also damage the overall sensing performance of these hydrogen sensors. Therefore, a new bilayer design with a Pd/In 2 O 3 sensitive layer and an In 2 O 3 /Al 2 O 3 catalytic filter layer is proposed to avoid the deactivation of hydrogen sensors. The In 2 O 3 /Al 2 O 3 layer helps in hindering HMDSO and its decomposition products from reaching the Pd/In 2 O 3 layer. The H 2 response of the sensors is enhanced due to the small size of In 2 O 3 and the electronic sensitization of Pd. As a result, the bilayer sensors exhibit high response (Ra/Rg = 53) and ultra-fast response time (1 s) towards 3000 ppm H 2 at 365 °C. The resistance and the H 2 response of the bilayer sensors are almost unchanged after 40 min of 10 ppm HDMSO poisoning. In this paper, the mechanism of resistance against silicone poisoning and the H 2 response of the bilayer sensors are discussed from the separation of sensing and catalytic filtration reactions to the behavior of adsorbed oxygen.
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Molecular Catalysis
·
2023
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IF 4.6
Mengling Dong,Tao Li,Jiacheng Xu,Tiantian Zhang,Yan Sun,Ning Li,Zuliang Wu,Jing Li,Erhao Gao,Jiali Zhu,Shuiliang Yao,Yong Huang
Methane (CH 4 ) is the second largest greenhouse gas; its emission should be controlled. A plasma reactor coupled with a catalyst was used to control CH 4 emission via oxidation. Compared with the traditional catalytic process, the activity of Pd/ZrO 2 /Al 2 O 3 catalyst is significantly improved, the light-off temperature ( T 50 ) is at a level of 290 °C. X-ray photoelectron spectroscopy characterization results proved that synergetic effect of plasma and catalysis on CH 4 oxidation was due to the increase in the amount of lattice oxygen on zirconia after plasma oxidation and the enhancement of the oxidation of Pd 0 to PdO on 1.0Pd/10ZrO 2 /γ-Al 2 O 3 catalyst. An operando plasma diffuse reflectance infrared Fourier transform spectroscopy mass spectrometer was used to demonstrate that CH 4 oxidation on Pd/ZrO 2 /Al 2 O 3 catalyst. It was found that 1.0Pd/10ZrO 2 /γ-Al 2 O 3 with plasma can efficiently promote CH 4 oxidation and convert surface formate and carbonate to gaseous CO 2 and H 2 O. The plasma-generated O atoms can react with surface H 2 O to yield reactive OH radicals which can obviously improve CH 4 oxidation at a temperature higher than 130 °C, this finding provides important enlightenment for the development of catalysts for plasma catalytic oxidation of CH 4 . The mechanism of CH 4 plasma-catalysis oxidation was discussed.
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APPLIED SURFACE SCIENCE
·
2022
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IF 7.392
Zuqin Duan,Xue Wang,Richu Wei,Qian Lei,Honglin Chen
A facile novel B, N co-doped carbon was fabricated by high-temperature pyrolysis of a mixture of ethylenediamine tetraacetic acid disodium salt and boric acid, on which Pd nanoparticles were loaded to synthesize highly efficient Pd/BNC catalyst for dehydrogenation of formic acid. The type and content of N are regulated by the doping of B elements in carbon materials. The high content of N and B doping provides more anchor sites for Pd and strengthens the interaction between the support and Pd nanoparticles, thus forming highly dispersed Pd nanoparticles and regulating the electronic property of Pd. Therefore, the obtained Pd/BNC catalyst displayed enhanced performance (TOF = 2760 h −1 ) and a lower activation barrier (31.84 kJ/mol). Furthermore, the catalyst also exhibited wonderful cycling stability for hydrogen evolution from formic acid.
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Molecular Catalysis
·
2023
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IF 4.6
Weikun Chen,Xiao Fu,Xiaoying Liu,Linmin Ye,Youzhu Yuan
N -alkylated piperazines can be synthesized by the thermal catalytic alkylation of piperazine with alkyl halides or alcohols in the presence of supported metal catalysts. However, these processes either discharge large amounts of waste or require harsh conditions. Here, we report the results of N -alkylation of piperazine with lower alcohols (methanol, ethanol, and propanol) without external hydrogen addition at room temperature in the presence of a TiO 2 -supported Pd catalyst (Pd/TiO 2 -P) prepared by photodeposition method. Compared with the catalysts prepared by the conventional chemical reduction or hydrogen reduction, the Pd/TiO 2 -P catalyst showed the highest conversion of piperazine and the best selectivity to N -alkypiperazines. The mechanistic studies indicated that this phenomenon occurs via tandem photocatalytic reactions involving alcohol dehydrgenation to aldehyde, aldehyde condensation with piperazine to enamine, and enamine hydrogenation to N -alkylated piperazines. Considering the experimental results of methanol isotope kinetics, the α-C–H cleavage of methanol to form hydroxymethyl radical (·CH 2 OH) was proven to be the rate-determining step in the N -alkylation reaction of piperazine with low carbon alcohols. The characterization and control experiments revealed that the size of Pd nanoparticles and the valence of Pd species were vital to the reaction. The Pd/TiO 2 -P catalyst with an average of 2.5 ± 0.5 nm Pd particles and approximately 68% Pd 0 species on surfaces presented the highest activity for the photocatalytic tandem reactions of methanol dehydrogenation and enamine hydrogenation.
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International Journal of Electrochemical Science
·
2023
·
IF 1.5
Zhentao Li,Yanhui Fu,Qingsheng Zhu,Saijin Wei,Jie Gao,Yifu Zhu,Ting Xue,Ling Bai,Yangping Wen
Phosphorene (BP) is a rapidly rising star in two-dimensional (2D) layered nanomaterials beyond graphene, and its urgent issues of ambient instability still have to be resolved. Here, the bimetallic Pt-Pd nanoparticle on the BP surface was employed as multifunctional chemical and biochemical sensing platform for electrocatalytic detection of p -aminophenol (PAP), β-galactosidase (β-Gal), and Escherichia coli ( E. coli ). The BP-supported Pt-Pd nanoelectrocatalyst obtained by the electrodeposition of bimetallic Pt-Pd nanoparticle onto the BP surface was very stable in aqueous buffer containing oxygen, which displayed good voltammetric responses for PAP in a linear range of 0.02 -5 μmol·L -1 with a detection limit (LOD) of 1.41 × 10 −8 M and sensitivity 115.81 μA·μM -1 ·cm -2 . PAP could be obtained by the biochemical reaction of β-Gal in the presence of substrate PAP-β-galactopyranoside, which could realize for biochemical sensing of β-Gal in a linear range of 0.2 -0.8 mU·L -1 with a LOD of 9.35 nU·L -1 and sensitivity of 4.77 μA (mU·L -1 ) -1 ·cm -2 . The β-Gal is an indicator of total coliforms represented by E. coli that are induced by isopropyl-β-thiogalactopyranoside, which could applied for biochemical sensing of E. coli in a linear range of 6 × 106 –1.6 × 108 cfu·mL-1 with LOD of 6.65 × 10 5 cfu·mL -1 and sensitivity of 2.44 μA·(cfu·mL -1 ) -1 ·cm -2 . This work will provide experimental support for multifunctional chemical and biochemical sensing platform based on 2D layered nanomaterials decorated with bimetallic nanoelectrocatalysts.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
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IF 4.326
Lian Duan,Chi Ma,Fengyan Lou,Jiabin Yin,Le Sang,Jisong Zhang
External mass transfer performance of micropacked bed reactors (μPBRs) with Pd/Al2O3/nickel foam catalysts is investigated by the hydrogenation of α-methylstyrene (AMS). The external mass transfer limitation region for AMS hydrogenation can be determined by means of the apparent activation energy and internal effectiveness factor. Parametric studies for external mass transfer are conducted by varying temperatures, operating pressures, liquid viscosities, gas and liquid superficial velocities, and pore diameters of foam packing. The external volumetric mass transfer coefficients [(ka)OV] of μPBRs with the Pd/Al2O3/nickel foam range from 0.06 to 0.71 s–1. An empirical correlation of (ka)OV is developed. Based on the gas–liquid–solid process analysis, the external mass transfer of μPBRs with the Pd/Al2O3/nickel foam is limited by liquid–solid mass transfer under the experimental conditions. Moreover, μPBRs with the Pd/Al2O3/nickel foam exhibit the best energy efficiency in comparison with that of other multiphase reactors.
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CARBON
·
2022
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IF 11.307
Xiang Yu,Yue Zhan,Tingting Fan,Yuqi Zhang,Shunqin Liang,Limin Sun,Xiaoli Hu,Weiping Fang,Zhou Chen,Xiaodong Yi
The stabilization and transport of the reactants, intermediates and products are significant to rational design of an industrial catalyst. In this work, we encapsulated the surface of Pd/g-C 3 N 4 catalyst with acrylic acid (AA) using a photo-induced grafting method to mimic the 3-dimensional nature of enzymes. A combined characterization and ab initio calculation revealed that AA ligands on the surface controlled the adsorption and diffusion behaviors of the reactants, rather than alter the electronic or geometric properties of Pd active centers. The optimized catalyst (Pd/CNA-4) significantly enhances isoprene partial hydrogenation activity without a decline in semi-hydrogenation selectivity. This approach can be further optimized by changing the types of the encapsulating ligands and can meet other specific catalytic reactions to regulate their conversion and selectivity and is therefore expected to extend to other areas of heterogeneous catalysis .
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Chemical Science
·
2022
·Vol. 13
·期 46
·13956-13965
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IF 9.969
Chen Wang,Wei Gao,Xinhao Wan,Bin Yao,Wenjing Mu,Jie Gao,Qiangang Fu,Dan Wen
Improving the utilization of noble metals is extremely urgent for fuel cell electrocatalysis, while three-dimensional hierarchical noble metal aerogels with abundant sites and channels are proposed to reinforce their electrocatalytic performances and decrease their amounts. Herein, novel Pd aerogels with tunable surface chemical states were prepared through a facile in situ electrochemical activation, starting with PdOx aerogels by the hydrolysis method. The hierarchical porous Pd aerogels showed unprecedented high activity towards the electrocatalytic oxidation of fuels including methanol (2.99 A mgPd−1), ethanol (8.81 A mgPd−1), and others in alkali, outperforming commercial catalysts (7.12- and 13.66-fold, corresponding to methanol and ethanol). Theoretical investigation unveiled the hybrid surface states with metallic and oxidized Pd species in Pd aerogels to regulate the adsorption of intermediates and facilitate the synergistic oxidation of adsorbed *CO, resulting in enhanced activity with the MOR as the model. Therefore, efficient Pd aerogels through the in situ electrochemical activation of PdOx aerogels were proposed and showed great potential for fuel cell anodic electrocatalysis.
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PubMed
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APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Zhuping Li,Yong Men,Shuang Liu,Jinguo Wang,Keye Qin,Dandan Tian,Tianle Shi,Li Zhang,Wei An
The crystalline phases of support have great influence on their surface and structure properties. Therefore, adjusting the crystalline structure of heterogeneous catalysts imposes a significant impact on the catalytic performance. Herein, a suite of Pd/In 2 O 3 /ZrO 2 catalysts with different crystalline phases of ZrO 2 were prepared and evaluated for CO 2 hydrogenation to CH 3 OH using the same amount of metal loading. The activity data showed the distinct superior reactivity of Pd/In 2 O 3 /ZrO 2 catalyst used mixed monoclinic and tetragonal phases ZrO 2 (Mix-ZrO 2 ) as support as compared to respective single phase of monoclinic ZrO 2 (m-ZrO 2 ) and tetragonal ZrO 2 (t-ZrO 2 ). The catalysts are extensively characterized through BET, XRD, HRTEM, UV–vis, H 2 -TPR, CO 2 /H 2 -TPD and XPS. Combining the characterization results and activity data, the superior activity of Pd/In 2 O 3 /Mix-ZrO 2 catalyst can be correlated with large particle size of Pd nanoparticles, the concentration of oxygen vacancies, and the abundant medium basic sites, which were essential for activation of H 2 and inert CO 2 and enhancement of catalytic performance. The best-performing Pd/In 2 O 3 /Mix-ZrO 2 catalyst exhibited a remarkable reactivity with space time yield (STY) of 0.54 g methanol ·h −1 ·g cat −1 at 573 K and 5 MPa, and stability without noticeable deactivation after 100 h of time on stream, demonstrating its potential as catalyst used in CH 3 OH synthesis from CO 2 hydrogenation.
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