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... 12−14 At present, the catalysts used for methane catalytic combustion are mainly divided into non-precious metal catalysts and precious metal catalysts. 15,16 The non-precious metal catalysts are low in price, easy to obtain, and have strong thermal stability, 17 especially the high catalytic activity and thermal stability of perovskites, which has attracted wide attention. 18−20 In recent years, the LaCoO 3 perovskite plays a very important role in surface catalytic reactions and surface chemical reactions. ...
In this paper, the methods of spin polarization density functional theory and vasp software package are used to simulate the adsorption of H2O molecules on the surface of LaCoO3 and La2CoFeO6(001). It was found that when Fe was doped at B-sites, the adsorption energy changed from -3.7493 eV at CoO2 to -2.5397 eV at CoFeO4, which decreased by about 1/3. Meanwhile, the change of electric charge and the amount of electron transfer decreased overall. The results indicated that Fe doping could inhibit the adsorption of H2O by perovskites and thus hinder the next toxic reaction. Therefore, this paper will lay a certain theoretical foundation for the study of perovskite anti-poisoning mechanism and provide a meaningful reference for further experimental research.
... Transition metal such as gold (Au), silver (Ag), platinum (Pt), and palladium (Pd), as well as lithium (Li), and rare earth elements (REEs) such as lanthanum (La), samarium (Sm), europium (Eu), and dysprosium (Dy) are more commonly utilized to manufacture electronics and superconducting magnets, respectively, therefore the higher the demand for the technology also indicates requirement for greater supply of these metals. Consequently, the main dilemma facing the growth of technological demand is the scarcity of supply of critical materials because not only critical materials are used for electronics but also for other scientific and non-scientific applications for example in catalysis [6,7], cosmetic dentistry [8,9], and as security markers [10], to name a few. ...
Critical materials (rare earth elements and lithium) are crucial components in the fabrication of advanced technologies. Local source from mining, especially in the United States, is very limited that recovery of these materials from secondary sources such as those in aqueous matrix like industrial effluents and brine is becoming imperative. Recovery of critical materials from aqueous matrix using commercialized adsorbents by solid-phase extraction is efficient but a costly operation. One approach taken to reduce the overall cost is to utilize marine polysaccharide-based biopolymeric hydrogels as an economical alternative to the costly commercialized adsorbents. Unlike its counterparts, the application of marine polysaccharide-based biopolymeric hydrogels to resource recovery presents a complex adsorption chemistry that can be accounted for by the fabrication strategies implemented. The lack of collective foundational understanding of different removal mechanisms presented by these class of adsorbents may hinder creative strategies to fabricate ion-selective hydrogels. This review highlights the different methodologies to synthesize hydrogel system of the three most abundant marine polysaccharide-based hydrogels namely chitosan, alginates, and carrageenan, their adsorption/desorption performance, and proposed adsorption/desorption mechanisms in rare earth elements recovery and direct lithium extraction from an aqueous matrix. This work also scrutinized the recovery efficiency of recently reported hydrogel materials for critical materials recovery and proposed key questions to serve as inception in the design conceptualization of hydrogel materials suitable for this application.
... Research interest in catalytic hydrogenation of nitroaromatic compounds (NCs) is due to the process feasibility in the manufacturing of aminoaromatic compounds (ACs) that are important intermediates in pharmaceutical, chemical (dyes, polymers), and agrichemical industries [1,2]. At the same time, the NCs are toxic and carcinogenic pollutants in wastewaters, and removal of the substances is an up-to-date challenge [3]. ...
The catalytic activity of the SBA-15-supported silver and/or ceria catalysts in the 4‑nitrophenol reduction under mild conditions is described. The catalysts are prepared by wetness impregnation of Pluronic [email protected] hybrid applied to stabilize small Ag and CeO2 particles. The bare SBA-15 and the catalysts on the basis thereof are characterized by N2 sorption, XRD, SAXS, TEM, UV-vis DRS, and H2-TPR. The catalysts possess high surface area (594-754 m²/g) and narrow pore size distributions (5.5-7.8 nm). Silver and ceria particles are stabilized in a highly dispersed state (predominant sizes below 5 nm) in the ordered SBA-15 structure. The Ag–CeO2/SBA-15 catalyst demonstrates the presence of the developed Ag–CeO2 interface that enhances the catalytic activity in 4-nitrophenol reduction to 4‑aminophenol (k = 0.016 s⁻¹) at room temperature and ambient pressure due to the cooperation of silver and ceria active sites.
... Platinum-based catalysts are widely used throughout industry. [1] Major applicationsi nclude:t he reduction of nitroarenes to aromatic aminoarenesf or use in polyurethane manufacture, [2] as ac omponent in the three-way automotive catalyst, [3] as the anode in polymer electrolyte membrane fuel cells (PEMFC) [4] ,a nd in chemotherapy. [5] Many of the uses of platinum arise from the facile [6] dissociation of dihydrogen at the catalysts urface. ...
The interaction of hydrogen with platinum is enormously important in many areas of catalysis. The most significant of these are in polymer electrolyte membrane fuel cells (PEMFC), in which carbon‐supported platinum is used to dissociate hydrogen gas at the anode. The nature of adsorbed hydrogen on platinum has been studied for many years on single‐crystal surfaces, on high‐surface area‐platinum metal (Raney platinum and platinum black), and on supported catalysts. Many forms of vibrational spectroscopy have played a key role in these studies, however, there is still no clear consensus as to the assignment of the spectra. In this work, ab initio molecular dynamics (AIMD) and lattice dynamics were used to study a 1.1 nm nanoparticle, Pt44H80. The results were compared to new inelastic neutron scattering spectra of hydrogen on platinum black and of a carbon‐supported platinum fuel cell catalyst and an assignment scheme that rationalises all previous data is proposed.
... Due to the aforementioned limitations of the commonly used catalysts in glucose and furfural hydrogenation reactions, noble metal catalysts, mainly based on Pt and Pd, have been studied, as they are known to exhibit high activity, strong deactivation resistance, and regeneration ability in different catalytic reactions [38][39][40]. While the Pd catalytic systems have exhibited total conversion or C-C bond cleavage leading to unwanted products, the Pt catalysts have showed higher selectivity at comparatively lower conversions [17,19,[41][42][43]. ...
Mono and bimetallic catalysts based on Pt and Pd were prepared by a co-precipitation method. They were tested in liquid phase hydrogenation reactions of glucose and furfural at low temperature and pressure. The bimetallic PtPd/TiO 2 catalyst proved to be an efficient material in selectively hydrogenating glucose to sorbitol. Moreover, high furfural conversion was attained under relatively soft conditions, and the furfuryl alcohol selectivity was strongly affected by the chemical composition of the catalysts. Furfuryl alcohol (FA) was the major product in most cases, along with side products such as methylfuran (MF), furan, and traces of tetrahydrofuran (THF). These results showed that the PtPd bimetallic sample was more active relative to the monometallic counterparts. A correlation between the catalytic results and the physicochemical properties of the supported nanoparticles identified key factors responsible for the synergetic behavior of the PtPd system. The high activity and selectivity were due to the formation of ultra-small particles, alloy formation, and the Pt-rich surface composition of the bimetallic particles supported on the TiO 2 nanowires.
... Most industries sector nowadays chooses to incorporate a catalyst in their process to increasing the activity or selectivity of the reaction. The advances in catalyst preparation has prompted renewed interest in catalyst preparation and modification [1,2]. One of the factors governing the activity of a catalyst is the metal -support interaction. ...
... The advance and flexibility in metal -catalyst interaction has contributed to a widely potential application [1]. Capability of each prospect metal to enhance the activity of catalytic reaction have urged more study to be performed to observe the effect the metal -support catalyst interaction on the catalytic conversion [1][2][3][4]. ...
... The advance and flexibility in metal -catalyst interaction has contributed to a widely potential application [1]. Capability of each prospect metal to enhance the activity of catalytic reaction have urged more study to be performed to observe the effect the metal -support catalyst interaction on the catalytic conversion [1][2][3][4]. The interaction of metal and the support has enhanced the activity, selectivity and the strength of the catalyst produce [3,4]. ...
A mesoporous zeolite silica alumina supported catalyst was impregnated with 3% Fe using different method of impregnation. This study focusing in finding the best impregnation method with the highest metal loaded and highly dispersion of impregnated metal. The impregnation methods carried out are wet impregnation, sono-chemical impregnation and point zero charge (PZC) impregnation. All prepared catalysts were analysed using AAS and FESEM to see the effective impregnation method. Based on the result, sono-chemical impregnation showed the highest actual Fe impregnated into the supported catalyst at 2.6 wt.% and 4.0 wt.% as detected by AAS and FESEM-EDX respectively.
... This 'tuning effect' is typically applied to oxidation catalysts to be used in automotive depollution application, like Pt on ceria [Jones (2016), Gäntzler (2017)]. Precious metals based catalysts also offer the intrinsic advantages of precious metals, like their chemical resistance (for example, they do not dissolve in alkaline or acidic solutions), which makes them very suitable for a large range of industrial applications [Muroi (2012)]. In the case of the Pd/Al2O3 system (Pd nanoparticles supported on various alumina supports), typical applications are summarized in Table 2.1 (in bold are particularly related to Pd/Al2O3); they mainly concern petrochemical and environmental catalyst applications. ...
In the beginning of the XXIst century, Environmental Transmission Electron Microscopy has become one of the reliable characterization techniques of nanomaterials in conditions mimicking their real life. ETEM is now able to follow the dynamic evolution of nanomaterials under various conditions like high temperature, liquid or various gas pressures. Among various fields of research, catalysis can benefit significantly from Environmental Microscopy. This contribution starts with the study of the Palladium-Alumina catalytic system. Pd nanoparticles supported by α-Al2O3 and δ-Al2O3 are of an important physicochemical and environmental interest, particularly in the field of selective hydrogenation in petrochemistry, for the synthesis of polymers or CO2 hydrogenation for methane production. We first performed 2D analyses at different steps of the synthesis process, then the same synthesis steps were performed under in situ conditions. The motivation of this approach was to compare post mortem treatments with ETEM observations. In general, 2D data provide limited insights on, for example, the morphology and position of supported nanoparticles. We have then developed a new fast acquisition approach to collect tomographic tilt series in very short times, enabling to reconstruct nano-systems in 3D during their dynamical evolution. Taking advantage of this approach, we have determined the activation energy for soot combustion on YSZ oxidation catalysts for diesel motors from volumetric data extracted from in situ experiments. Fast electron tomography was also applied to electron beam sensitive materials, like polymer nanocomposites and biological materials, showing the wide spectrum of possible applications for rapid 3D characterization of nanomaterials.
... Precious metals dissolve in acidic media under oxygen. Hence, Pt loss is related to corrosion in acid via the oxidation of Pt components [31]. At a low reaction temperature, the oxygen evolution rate is low. ...
The Pt/SiC-AP catalyst is prepared by the polyol method using acid treated SiC for sulfuric acid (SA) decomposition, which exhibits the highest activity and stability among the Pt/SiC catalysts prepared by four different methods. In a longer-term stability test at 850 °C and a GHSV of 53,500 mL/gcat/h for 30 h, the Pt/SiC-AP catalyst shows the SA conversion of 82%. The activity loss of the Pt/SiC-AP catalyst is observed at 15 h, but the catalyst is almost stabilized at the SA conversion of ca. 78% afterwards. The Pt loss with the Pt/SiC-AP catalyst is the least among the prepared catalysts. Most of Pt loss with the Pt/SiC-AP catalyst occurs within 5 h during the phase change from Pt/SiC to Pt/SixCyOz/SiC and the Pt loss is rarely observed for 30 h thereafter. The acid treatment of the SiC support improves the catalytic stability by enhancing the interaction between Pt and SiC and the Pt/SiC catalyst with well-dispersed Pt particles is obtained by using the polyol method.
Graphical Abstract
... Automotive three-way catalysts (TWC) based on Pt, Pd and Rh have been designed and manufactured with the objective to improve air quality and protect human health. The presence of the platinum group metals (PGMs) provides a distinguishing effectiveness for the conversion of hydrocarbons (HCs), carbon monoxide (CO) and nitrogen oxides (NO x ) [1,2]. Furthermore, their outstanding stability guarantees a long catalyst on-road life span. ...
Supported copper oxide nanoparticles are a potential candidate for replacing the rare and expensive precious metals within the automotive three-way catalyst. However, a well-designed dispersion method is necessary to allow a stable high loading of active material, compensating its lower intrinsic activity and stability. In this work, a CuO-loaded SBA-15 catalyst has been manufactured by two methods. The ammonia-driven deposition precipitation (ADP) and the molecular designed dispersion (MDD) methods are both considered as efficient deposition methods to provide well-dispersed copper oxide-based catalysts. Their morphology, copper dispersion and the chemical state of copper were characterized and compared. Due to the differences in the synthesis approach, a difference in the obtained copper oxide phases has been observed, leading to a distinct behavior in the catalytic performance. The structure-activity correlation of both catalysts has also been revealed for automotive exhaust gas abatement. Results demonstrate that various copper species can be formed depending on the precursor–support interaction, affecting selectivity and conversion during the catalytic reaction.
... These catalysts are widely employed for the hydrogenation of aromatics. The unique characteristics for the selection of these types of catalyst can be high dispersion of Pd, high surface area of carbon, low quantity of 54 There were many efforts to improve or replace the Pd/C catalyst since the lifetime of the catalyst is relatively short. Moreover, the carbon support can contaminate the PTA, and palladium is very expensive. ...
One of the key concerns of the purification section of purified terephthalic acid (PTA)
production plant is the deactivation of palladium supported on carbon (Pd/C) catalyst. In this
work, the deactivation rate model of 0.5 wt.% Pd/C catalyst has been developed considering
temperature, active surface area, and residual catalytic activity. Moreover, the optimal operating
conditions of the industrial hydropurification process has been investigated. The results show
that PTA production rate (PPR) can be improved by 5.4 percent through 18 percent increase in
hydrogen flowrate. Furthermore, PPR can be increased by 7.6 percent via the temperature rise in
the reaction mixture. The optimization results further reveal that PPR can be enhanced by 17.3
percent by improving the feed concentration under the normal operation by means of limiting the
inlet 4-carboxybenzaldehyde concentration. The research findings can be applied in the actual
working plant to enhance the efficiency of the hydropurification process.
