Research

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14 pages, 2215 KiB

Open AccessFeature PaperArticle

Vine Shoots and Grape Stalks as Carbon Sources for Hydrogen Evolution Reaction Electrocatalyst Supports

by J.A.S.B. Cardoso, B. Šljukić, M. Erdem, C.A.C. Sequeira and D.M.F. Santos

Catalysts 2018, 8(2), 50; https://doi.org/10.3390/catal8020050 - 27 Jan 2018

Cited by 9 | Viewed by 4203

Activated bio-based carbons produced from vine shoots (VSAC) and grape stalks (GSAC), which have larger surface area and total pore volume than most of the commercially available activated carbons, are used as supports for palladium nanoparticles (Pd NPs). The prepared materials are characterised [...] Read more.

Activated bio-based carbons produced from vine shoots (VSAC) and grape stalks (GSAC), which have larger surface area and total pore volume than most of the commercially available activated carbons, are used as supports for palladium nanoparticles (Pd NPs). The prepared materials are characterised by elemental analysis, N₂-sorption, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, and transmission electron microscopy analysis and are then assessed as potential cathodes for the hydrogen evolution reaction (HER) in alkaline media. The electrocatalysts’ performance for HER is evaluated from cathodic polarisation curves at different temperatures and compared to that of Vulcan XC72-supported Pd NPs. Additional chronoamperometry studies helped to assess the electrocatalysts’ activity stability. The novel VSAC-supported Pd electrocatalyst exhibits good HER activity in terms of high current density at low overpotentials, leading to the best performance. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis & Hydrogen Storage)

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3931 KiB

Open AccessArticle

Morpholine-Modified Pd/γ-Al₂O₃@ASMA Pellet Catalyst with Excellent Catalytic Selectivity in the Hydrogenation of p-Chloronitrobenzene to p-Chloroaniline

by Wei Wang, Wenlong Xu, Kedar Bahadur Thapa, Xiaorui Yang, Jinhua Liang, Liyan Zhu and Jianliang Zhu

Catalysts 2017, 7(10), 292; https://doi.org/10.3390/catal7100292 - 30 Sep 2017

Cited by 15 | Viewed by 5700

Abstract

An amino poly (styrene-co-maleic anhydride) polymer (ASMA) encapsulated γ-Al₂O₃ pellet material has been synthesized successfully. After loading with Pd species and modified with morpholine, the inorganic-organic hybrid material shows an excellent catalytic property in the selective hydrogenation [...] Read more.

An amino poly (styrene-co-maleic anhydride) polymer (ASMA) encapsulated γ-Al₂O₃ pellet material has been synthesized successfully. After loading with Pd species and modified with morpholine, the inorganic-organic hybrid material shows an excellent catalytic property in the selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN). In this procedure, morpholine can connect with the polymer layer in a form of amide bond and acts as an unparalleled immobilized dechlorination inhibitor, which can avoid further dechlorination efficiently and keeps stability due to the repulsive effect from the surviving C-O-C bond. The catalyst as prepared was characterized by using XRD, TGA, SEM, TEM, FT-IR, and ICP-OES, and it was further tested in the selective hydrogenation of p-CNB. It shows a supreme catalytic activity (almost 100%) and selectivity (up to 99.51%) after recycling for even 10 times, much superior to the blank alumina supported palladium (47.09%). Full article

(This article belongs to the Special Issue Heterogeneous Catalysis & Hydrogen Storage)

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4759 KiB

Open AccessArticle

Hydrogen Evolution Reaction of γ-Mo_0.5W_0.5 C Achieved by High Pressure High Temperature Synthesis

by Yingfei Hu, Gan Jia, Shuailing Ma, Jianqiang Hu, Pinwen Zhu, Tian Cui, Zhaosheng Li and Zhigang Zou

Catalysts 2016, 6(12), 208; https://doi.org/10.3390/catal6120208 - 17 Dec 2016

Cited by 5 | Viewed by 4920

Abstract

For the first time, the hydrogen evolution reaction (HER) electrocatalytic performances of incompressible γ-Mo_0.5W_0.5C, prepared by high-pressure, high-temperature (HPHT) synthesis, were investigated in the electrolyte. The polarization curve of the γ-Mo_0.5W_0.5C cathode exhibits the current [...] Read more.

For the first time, the hydrogen evolution reaction (HER) electrocatalytic performances of incompressible γ-Mo_0.5W_0.5C, prepared by high-pressure, high-temperature (HPHT) synthesis, were investigated in the electrolyte. The polarization curve of the γ-Mo_0.5W_0.5C cathode exhibits the current density of 50 mA∙cm⁻² at an overpotential value of 320 mV. The corresponding Tafel slope of the incompressible γ-Mo_0.5W_0.5C is 74 mV∙dec⁻¹. After a 1000-cycle test, and then exposure to the air for six months, the γ-Mo_0.5W_0.5C electrode performed a current density of 50 mA∙cm⁻² at an overpotential of 354 mV, which was close to the initial one. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis & Hydrogen Storage)

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7606 KiB

Open AccessArticle

Binary Oxides with Defined Hierarchy of Pores in the Esterification of Glycerol

by Nuryana Ferreira Alves, Antonio De Brito Santiago Neto, Bruno Dos Santos Bessa, Alcemira Conceição Oliveira, Josue Mendes Filho, Adriana Ferreira Campos and Alcineia Conceição Oliveira

Catalysts 2016, 6(10), 151; https://doi.org/10.3390/catal6100151 - 27 Sep 2016

Cited by 13 | Viewed by 5796

Abstract

Various porous binary oxides with elevated textural properties were obtained in this work. The as-synthesized solids were calcined or modified by reflux and extraction processes. Characterizations through SEM, nitrogen physisorption and TEM techniques demonstrated the formation of porous metal oxide networks over all [...] Read more.

Various porous binary oxides with elevated textural properties were obtained in this work. The as-synthesized solids were calcined or modified by reflux and extraction processes. Characterizations through SEM, nitrogen physisorption and TEM techniques demonstrated the formation of porous metal oxide networks over all solids. XRD, thermal analyses and FTIR measurements showed the existence of nanosized rutile TiO₂, tetragonal ZrO₂, SiO₂ and γ-Al₂O₃ phases on the solids. The structure and texture of the as-synthesized SiAl sol-gel derived solid resulted in the formation of well-dispersed nanoparticles on the support. The removal of the organic compounds by ethanol extraction or reflux from SiAl resulted in the presence of structures with defined hierarchy of pores. Among the solids studied, the catalytic results in the esterification of glycerol with acetic acid indicated that best performances were obtained over SiAl sample when submitted to extraction and reflux treatments. This was due to the creation of accessible pores, which facilitated the reaction occurrence at glycerol to acetic acid molar ratio = 1:3 and T = 80 °C for 20 h using 75 mg of catalyst. The solids can be reused three times without complete loss of their catalytic performance. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis & Hydrogen Storage)

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4349 KiB

Open AccessArticle

WS₂ as an Effective Noble-Metal Free Cocatalyst Modified TiSi₂ for Enhanced Photocatalytic Hydrogen Evolution under Visible Light Irradiation

by Dongmei Chu, Chunyong Zhang, Ping Yang, Yukou Du and Cheng Lu

Catalysts 2016, 6(9), 136; https://doi.org/10.3390/catal6090136 - 10 Sep 2016

Cited by 23 | Viewed by 7341

Abstract

A noble-metal free photocatalyst consisting of WS₂ and TiSi₂ being used for hydrogen evolution under visible light irradiation, has been successfully prepared by in-situ formation of WS₂ on the surface of TiSi₂ in a thermal reaction. The obtained samples [...] Read more.

A noble-metal free photocatalyst consisting of WS₂ and TiSi₂ being used for hydrogen evolution under visible light irradiation, has been successfully prepared by in-situ formation of WS₂ on the surface of TiSi₂ in a thermal reaction. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results demonstrate that WS₂ moiety has been successfully deposited on the surface of TiSi₂ and some kind of chemical bonds, such as Ti-S-W and Si-S-W, might have formed on the interface of the TiSi₂ and WS₂ components. Optical and photoelectrochemical investigations reveal that WS₂/TiSi₂ composite possesses lower hydrogen evolution potential and enhanced photogenerated charge separation and transfer efficiency. Under 6 h of visible light (λ > 420 nm) irradiation, the total amount of hydrogen evolved from the optimal WS₂/TiSi₂ catalyst is 596.4 μmol·g⁻¹, which is around 1.5 times higher than that of pure TiSi₂ under the same reaction conditions. This study shows a paradigm of developing the effective, scalable and inexpensive system for photocatalytic hydrogen generation. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis & Hydrogen Storage)

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4670 KiB

Open AccessArticle

Sulfide Catalysts Supported on Porous Aromatic Frameworks for Naphthalene Hydroprocessing

by Eduard Karakhanov, Yulia Kardasheva, Leonid Kulikov, Anton Maximov, Anna Zolotukhina, Maria Vinnikova and Andrey Ivanov

Catalysts 2016, 6(8), 122; https://doi.org/10.3390/catal6080122 - 16 Aug 2016

Cited by 23 | Viewed by 6382

Abstract

This paper describes the first example of using porous aromatic frameworks as supports for sulfide catalysts for the hydrogenation of aromatic hydrocarbons. The synthesis of bimetallic Ni-W and Ni-Mo sulfides was performed by in situ decomposition of [(n-Bu)₄N]₂[Ni(MeS₄ [...] Read more.

This paper describes the first example of using porous aromatic frameworks as supports for sulfide catalysts for the hydrogenation of aromatic hydrocarbons. The synthesis of bimetallic Ni-W and Ni-Mo sulfides was performed by in situ decomposition of [(n-Bu)₄N]₂[Ni(MeS₄)₂] (Me = W, Mo) complexes, supported on mesoporous aromatic framework with a diamond-like structure. It is shown that the highest naphthalene conversions were achieved in the case of additional sulfidation with sulfur. After the reaction, catalysts were characterized by X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. The activity of synthesized catalysts has been studied using naphthalene as a model substrate. The materials used in this study were substantially active in hydrogenation and slightly in hydrocracking of naphthalene. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis & Hydrogen Storage)

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Review

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22 pages, 5845 KiB

Open AccessReview

Catalysis and Downsizing in Mg-Based Hydrogen Storage Materials

by Jianding Li, Bo Li, Huaiyu Shao, Wei Li and Huaijun Lin

Catalysts 2018, 8(2), 89; https://doi.org/10.3390/catal8020089 - 23 Feb 2018

Cited by 59 | Viewed by 7144

Abstract

Magnesium (Mg)-based materials are promising candidates for hydrogen storage due to the low cost, high hydrogen storage capacity and abundant resources of magnesium for the realization of a hydrogen society. However, the sluggish kinetics and strong stability of the metal-hydrogen bonding of Mg-based [...] Read more.

Magnesium (Mg)-based materials are promising candidates for hydrogen storage due to the low cost, high hydrogen storage capacity and abundant resources of magnesium for the realization of a hydrogen society. However, the sluggish kinetics and strong stability of the metal-hydrogen bonding of Mg-based materials hinder their application, especially for onboard storage. Many researchers are devoted to overcoming these challenges by numerous methods. Here, this review summarizes some advances in the development of Mg-based hydrogen storage materials related to downsizing and catalysis. In particular, the focus is on how downsizing and catalysts affect the hydrogen storage capacity, kinetics and thermodynamics of Mg-based hydrogen storage materials. Finally, the future development and applications of Mg-based hydrogen storage materials is discussed. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis & Hydrogen Storage)

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7879 KiB

Open AccessReview

Controllable and Large-Scale Synthesis of Carbon Nanostructures: A Review on Bamboo-Like Nanotubes

by Zirui Jia, Kaichang Kou, Ming Qin, Hongjing Wu, Fabrizio Puleo and Leonarda Francesca Liotta

Catalysts 2017, 7(9), 256; https://doi.org/10.3390/catal7090256 - 30 Aug 2017

Cited by 47 | Viewed by 7633

Abstract

Bamboo-like carbon nanotubes are members of the carbon nanotubes (CNTs) family, whose structure is made up of separated hollow compartments and bamboo knots. Due to the peculiar structure of the CNTs species, the growth mechanism and related features have been widely investigated. Bamboo-like [...] Read more.

Bamboo-like carbon nanotubes are members of the carbon nanotubes (CNTs) family, whose structure is made up of separated hollow compartments and bamboo knots. Due to the peculiar structure of the CNTs species, the growth mechanism and related features have been widely investigated. Bamboo-like carbon nanotubes are widely applied in several fields, such as sensors, adsorbents, catalysts, and lithium-ion battery electrodes materials. Different methods have been applied for the synthesis of carbon nanotubes, among them, catalytic chemical vapor deposition has been singled out as the most used procedure due to low cost with a high quality product. The present review is devoted to increasing the literature dealing with the design, synthesis, and characterization of bamboo-like carbon nanotubes grown over different catalysts. Results on the methane dry reforming reaction, hydrocarbon thermal decomposition, special chemical vapor deposition as well as other methods applied to the preparation of bamboo-like carbon nanotubes are discussed. The differences in the carbon deposits between the dry reforming reaction and other reaction methods are compared and possible formation mechanisms of bamboo-like carbon nanotubes are discussed. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis & Hydrogen Storage)

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