Urea Precipitation Method Research Articles

Evaluation of a novel nickel ceramic filter prepared by urea precipitation method for removal of tars from biomass syngas using naphthalene as tar model compound

Gasification has been shown to be an effective thermal conversion process for waste biomass in order to create fuel, specialty chemicals, and hydrogen. Gasification is likely to take on a major role in the near future in the burgeoning hydrogen economy. In order to improve the commercial viability of gasification, catalytic tar reforming has come to the forefront as one of the most promising methods of reducing the tar content that has been detrimental to downstream equipment in the process. The use of catalytic ceramic filters has presented promising potential for this application that can serve dual role of tar and particulate removal. In this study, a nickel-based ceramic filter has been prepared using urea vacuum impregnation technique and evaluated for tar removal efficiencies. The urea technique was more effective than traditional impregnation techniques at uniformly dispersing nickel across the surface of the ceramic filter, driving the nickel particles to penetrate the pores of the support, thus aiding in improved tar removal capabilities. Through steam reforming studies using a naphthalene simulant tar molecule, the 15 wt% nickel filter was able to reduce the naphthalene content by 97% at temperature of 750 °C over 2 h. An activation energy of 126.4 kJmol was achieved for steam reforming using the urea vacuum impregnated catalytic filter compared to 136.4 kJmol using the incipient wetness impregnated filter.

Structural and morphological characterization of Y1-xNdxAl3(BO3)4 micron-sized crystals powders obtained by the urea precipitation method and its random laser properties

The search for efficient photonic materials for laser action has grown since 1960, after the invention of the ruby laser. Among the elements that exhibit stimulated emission, Nd3+ has received great attention for use in conventional or random lasers. Several host matrices have been developed for lanthanides ions, and aluminum borates (as YAl3(BO3)4, YAB) have proven to be excellent laser hosts due to their physicochemical properties. YAB can be synthesized by various routes, including flux methods, the Pechini method, and the sol–gel methodology. We report a new synthesis route to prepare Y1-xNdxAl3(BO3)4 micron-sized crystals, x = 0.1, 0.2, 0.4, 0.6, or 0.8, on the basis of the urea precipitation method. Structural characterization confirmed that all the particulate samples have trigonal symmetry with hexagonal space group. Powder X-Ray Diffraction (PXRD), High-Resolution Transmission Electron Microscopy (HRTEM), and Selected Area Electron Diffraction (SAED) showed that the particles are well crystallized. Photoluminescence studies revealed that Nd3+ replaces Y3+ in the YAB host matrix. Stimulated emission leading to random lasing in the Nd3+:YAB powder is demonstrated, which also opens the possibilities of its use as efficient materials for superluminescent sources.

Understanding relationship of sepiolite structure tailoring and the catalytic behaviors in glycerol steam reforming over Co/sepiolite derived Co-phyllosilicate catalyst

Bio-glycerol Steam reforming over green and economical Co/sepiolite (SEP) catalysts was a promising strategy to hydrogen production. The activation pretreatment of SEP played a vital role for boosting catalytic behavior of Co/SEP. This work originally explored a full activation of SEP by molten NaOH for tailoring the physicochemical properties of Co-based catalysts prepared by urea precipitation method. Differing from the acid pickling/calcination and molten NaNO3 activation, the molten NaOH treatment enhanced surface area of SEP by desilicication/dealumination effect and further improved the exposure of framework Si and its surface ‘reactivity’. According to the characterization results of N2 adsorption-desorption, XRD, TEM, H2-TPR, CO/CO2-TPD and XPS, it was found that the feathered Co-phyllosilicate formed on Co/SEP-NaOH catalyst, which enhanced the metal-support interaction, surface area and basic/metallic sites. In contrast, the molten NaNO3 treatment facilitated the transformation of SEP into loughlinite and it was adverse to metal dispersion. Therefore, Co/SEP-NaOH catalyst possessed the highest conversion (92%) and H2 yield (68%) during the activity test at 600 °C and the superior resistance to amorphous coke. Additionally, DFT analysis was introduced to simulate the process of glycerol adsorption and decomposition and demonstrated the Co–CoO interface as the primary reaction sites for the catalytic process.

Urea-Assisted Synthesis of Nanospherical and Plate-Like Magnesium Oxides for Efficient Removal of Reactive Dye Wastes

Nanospherical and plate-like magnesium oxide has been successfully synthesized by urea precipitation method for the first time. A magnesium oxide precursor was prepared by heating MgCl2 solution with urea for 12 hours at 90°C. Then the calcined precursor was analysed by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and high-resolution transmission electron microscopy (HR-TEM). In the presence of the nonionic surfactant Triton X-100 in the system, the reaction yielded in nanospheres of MgO contrast to the plate-like MgO in the absence of the surfactant. The precursor and the calcined product appeared in similar morphologies under SEM in both cases with a slight reduction of size upon calcination. The final product was confirmed as MgO using XRD and FT-IR spectroscopic methods. In TGA, both samples showed similar mass loss values upon elimination of adsorbed water molecules and decomposition of the precursor into MgO; however, the nanospherical MgO sample showed an additional weight loss due to elimination of the associated surfactant molecules. The efficiency of removing reactive dye wastes was quantified by UV-visible spectroscopy using reactive yellow dye. Plate-like MgO showed a porous structure under HR-TEM analysis in the dye adsorption study, and both plate-like and nanospherical MgO showed good dye adsorption capability. MgO nanospheres showed higher capacity of dye adsorption compared to plate-like MgO, explained by its higher surface are-to-volume ratio, while the plate-like MgO also performed well due to having a nanoporous structure. These nanomaterials will offer high potential in purifying waste water and as well in recovering expensive dye products.

Highly stable low noble metal content rhodium-based catalyst for the dry reforming of methane

The catalytic performance of different nickel- and rhodium-based catalysts supported on γ-Al2O3 was investigated for the dry reforming of methane (DRM) reaction. The catalysts were prepared either by the incipient wetness impregnation method (IWI) or urea precipitation method (UPM) and characterized by XRD, TPR, XRF, BET, and H2 chemisorption techniques. Long-term reactions were performed in a fixed bed reactor over the temperature range of 700–800 °C, WHSV 12–108 h−1, and with a CH4:CO2 feed ratio equal to unity. All nickel-based catalysts tested, despite presenting high CH4 and CO2 conversions in the first reaction moments, underwent deactivation and long-term performance losses. On the other hand, a low rhodium content tested catalyst, 0.1%Rh/Al2O3, exhibited a remarkable performance with CH4 and CO2 conversions compatible with the thermodynamic conversions and an H2/CO ratio close to 1. Moreover, the catalyst presented exceptional stability with no visible signs of deactivation over more than 180 h on stream. Therefore, the aforementioned catalyst represents an important contribution to the dry reforming of methane technology, since it exhibited high conversions, exceptional stability, and very low noble metal content.

Improved Norfloxacin degradation by urea precipitation Ti/SnO2–Sb anode under photo-electro catalysis and kinetics investigation by BP-neural-network-physical modeling

The photo-electro catalysis has emerged as efficient and sustainable degradation method for antibiotics, where metal oxide anode plays a critical role. Exploring novel preparation method for anodes catalysis to achieve larger active sites and diverse oxidants production can directly enhance the degradation performance. Therefore, in this work, a new urea precipitation method for anode formation was studied. Both novel urea precipitation Ti/SnO2–Sb anode (TSSA-U) and traditional electro-deposition Ti/SnO2–Sb anode (TSSA-E) were prepared for Norfloxacin degradation by photo-electro catalysis in saline water. A unique tubular Ti/SnO2–Sb units formatted by urea precipitation resulted in higher porosity. This led to dominating advantage for TSSA-U on photo/electrochemical activity and degradation performances by individual photo/electro catalysis, compared to TSSA-E. However, this gap of degradation performances shrank when synergistic effect of photo-electro catalysis involved. The highest TOC removal ratio of 91.1% was obtained from TSSA-U under photo-electro catalysis. Besides, a novel BP-neural-network-physical modeling (BP-ANN-P) was developed for analysis. According to this modeling, both direct (adsorption-degradation, radiation, etc.) and indirect (mainly •Cl) routes contributed significantly in degradation work by TSSA-U, where indirect route shared 41.8–90.1% of total degradation ratio. An increasing of current density (from 5 to 25 mA cm−2) enhanced the kinetics for both routes. Indirect route preferred pH = 3–7 with direct route enhanced by neutral condition. Moreover, indirect route also showed better adaptability with higher initial NOR loadings.Both urea precipitation and BP-ANN-P have shown their value for high performance material formation and data analysis, respectively. Notably, higher catalysis performance and better analysis connect to low energy cost, shorter running time and more efficient judgement and selection, which meets the requirement of cleaner production and environmental sustainability.

Eu, Li codoped zirconia nanoparticles with enhanced optical properties

Abstract This study reports on the synthesis of Eu and Li-codoped zirconia ZrO2 nanoparticles (NPs) using a facile urea precipitation method. The morphology, structural and optical properties of prepared Eu, Li-codoped ZrO2 NPs were analyzed by transmission electron microscope (TEM), X-ray diffraction (XRD), and photoluminescence (PL), respectively. As the main goal of this study, we investigated the effects of Li-codoping on the optical properties of Eu-doped ZrO2 NPs. Strong eye-visible red emission due to 5D0→7F1 and 5D0→7F2 transitions was detected under continuous 250 nm excitation. Thanks to excellent optical properties, prepared Eu, Li-codoped ZrO2 NPs can be used for solid-state lighting, security printing, etc

Synthesis of monodisperse ZrO 2 microspheres via urea homogeneous precipitation and its effect on the sintering properties

Monodisperse zirconia microspheres were prepared by homogeneous urea precipitation method. The effect of reaction time, reaction temperature and other synthetic parameters on the dispersion of the product was investigated in this experiment. The as-prepared zirconium oxide (ZrO2) powders were characterised by X-ray diffraction, Brunauer–Emmett–Teller analysis, field emission-scanning electron microscopy and Fourier-transform infrared spectroscopy. The experimental results show that the size and dispersion of ZrO2 microspheres can be controlled by changing the concentration of polyvinylpyrrolidone (PVP). The size of ZrO2 microspheres is changed from 120 nm to 1 μm with the increase of PVP concentration. When the reaction temperature is raised to 90°C and the reaction time is reached to 2 h, the monodisperse ZrO2 microspheres with a diameter of 120 nm are finally prepared. ZrO2 ceramics possessed an ultrafine, uniform microstructure and a narrow pore size distribution, and the grain size increased from 72 to 190 nm with the increase of sintering temperature. Moreover, when ZrO2 ceramics were sintered at 950°C for 2 h, the theoretical density was up to about 98% (a density of 5.65 g/cm3), which is higher than that of conventional ZrO2 ceramics.

Semihydrogenation of phenylacetylene over nonprecious Ni-based catalysts supported on AlSBA-15

A series of nonprecious monometallic Ni/AlSBA-15 and bimetallic NiM (M = Zn, Ga, Cu, or Fe)/AlSBA-15 catalysts were prepared using a urea precipitation method and applied to the semihydrogenation of phenylacetylene. The catalysts were characterized by various techniques, showing that the Ni particle size of catalyst can be tuned by adjusting the Al content, and NiZn and NiGa supported catalysts exhibited geometric and electronic effects that originated from the bimetallic alloy. Among all the catalysts studied, NiZn3/AlSBA-15, with a turnover frequency of 10.89 s−1 comparable to that of precious Pd-based catalysts, presented the highest selectivity to styrene (90.3%) at nearly 100% conversion of phenylacetylene in semibatch operation. This catalyst was further evaluated in a continuous fixed-bed reactor for semihydrogenation of a model C8 aromatic fraction of pyrolysis gasoline (a mixture of phenylacetylene, styrene, ethylbenzene and xylene), which aimed at assessing its practical application of recovering styrene from pyrolysis gasoline. The results showed that at complete conversion of phenylacetylene, the styrene concentration in the product was always kept at a stable level and higher than its initial concentration over 100 h of time on stream, demonstrating high selectivity and good stability of NiZn3/AlSBA-15. Finally, the application of NiZn3/AlSBA-15 was extended to other phenylacetylene derivatives.

Activation of persulfate with 3D urchin-like CoO-CuO microparticles for DBP degradation: A catalytic mechanism study

Rational modification of the surface structure and interface structure can effectively optimize the catalytic performance and stability of a heterogeneous catalyst. A CoO-CuO bimetallic catalyst with a special urchin-like structure was prepared by a hydrothermal urea precipitation method. This carbon nanosphere template method significantly improves the dispersibility of the material. The special urchin-like nanorod structure expands the specific surface area, resulting in excellent adsorption performance and high catalytic performance. The materials were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The oxidative degradation mechanism of dibutyl phthalate (DBP) using sodium persulfate (SPS) activated by the CoO-CuO double metal oxide catalyst was explored. The synergy between the two metals gives the material a stable and highly catalytic ability.

Preparation of dispersed submicron YAG:Ce3+ phosphors via the molten salt method

Nano Ce-doped yttrium aluminum garnet (YAG:Ce) phosphor precursor was synthesized using the urea precipitation method, and dispersed submicron YAG:Ce phosphor was prepared using the molten salt method, with fine particle NaCl acting as the salt source. The effects of NaCl particle size on the mixing homogeneity of raw materials, particle morphology, dispersity, and luminescent properties of YAG phosphor were investigated. We found that the mixing homogeneity improved dramatically with a fine (2 µm) NaCl particle. Agglomeration and sintering of the phosphor were significantly reduced, and 200 nm dispersed YAG phosphor can be obtained at 1000 °C. The YAG phosphor obtained with fine NaCl salt also exhibits excellent luminous performance. The YAG phosphor blue light absorption ratio is 38%, and the internal quantum efficiency is 93%. The internal quantum efficiency is superior to YAG phosphors synthesized using commercial large-particle NaCl. These findings provide a new idea for preparing dispersed inorganic powder with fine particle size using the molten salt method.

Highly Stable Nb2O5–Al2O3 Composites Supported Pt Catalysts for Hydrodeoxygenation of Diphenyl Ether

Various TiO2, SiO2, Al2O3, and Nb2O5–Al2O3 supported Pt catalysts have been prepared by urea precipitation method for catalytic hydrodeoxygenation (HDO) of diphenyl ether (DPE) as a 4-O-5 aryl-ether lignin model compound. The selectivity toward deoxygenated product cyclohexane increased obviously with Nb2O5·nH2O decorated, owing to the significant promotion effect of NbOx species and acid sites on C–O bond cleavage. At higher pressure (3.0 MPa H2), DPE underwent a HYD route, while direct hydrogenolysis route occurred at low pressure (0.1 MPa H2). In addition, the reaction rate constants and activation energies were obtained in the temperature range from 160 to 220 °C. Based on the Arrhenius law, the activation energy for the cleavage of the C–O bond in DPE was calculated to be 91.22 kJ/mol. It was noteworthy that the Pt/20Nb–Al2O3 showed higher stability than Pt/Al2O3 for hydrodeoxygenation of diphenyl ether, which can be attributed to its water-tolerant Lewis acid sites.

Fe–Mn Mixed Oxide Catalysts Synthesized by One-Step Urea-Precipitation Method for the Selective Catalytic Reduction of NO x with NH3 at Low Temperatures

A range of Fe–Mn mixed oxide catalysts, FeαMn1−αO x (α = 1, 0.25, 0.33, 0.50, 0 mol%) were prepared via one-step urea-precipitation method and applied to the selective catalytic reduction (SCR) of nitric oxide (NO x ) with NH3. The Fe0.33Mn0.66O x catalyst showed the highest activity in the NH3-SCR process within a broad operation temperature range (75–225 °C) with 90% NO x conversion. Series of characterization have been taken to investigate the physical and chemical properties of the catalysts. The BET results evidenced that the doping of iron species increased the surface area of the catalyst effectively, and this structure could provide more acid sites and active sites on the surface of catalysts for SCR reaction. X-ray powder diffraction results and Raman spectroscopy indicate that the active Mn and Fe species were in poorly crystalline or amorphous states which could increase lattice defects and oxygen vacancies on the surface of Fe0.33Mn0.66O x catalyst. The X-ray photoelectron spectra results suggested that more surface-adsorbed oxygen (OA), Fe3+, Mn4+ species existed on the surface of the Fe0.33Mn0.66O x catalyst compared with that of MnO x and FeO x catalysts, which is favorable to the NH3-SCR performance. Analysis by in situ Fourier transform infrared spectroscopy (FTIR) suggested that Fe-doping can enhance the absorption and the activation ability of NO which could promote the catalytic performance in the SCR process. Catalyst characterization Powder X-ray diffraction (XRD) was carried out on a PAN alytical powder X-ray diffractometer (Model EMPYREAN) with a monochromatic Cu Kα1 radiation (λ = 0.154056 nm) within a 2θ range of 10°–90° in the step of 0.02° at room temperature. The Brunauer–Emmett–Teller (BET) surface areas of the samples were computed by physical adsorption of N2 at − 196 °C using a NOVA 1200 (Quanta Chrome). The samples were pretreated at 300 °C for 5 h in a vacuum state previous to BET measurement. The high-resolution transmission electron microscopy (HR-TEM) determinations were conducted on a JEOL-2100 microscope. The Raman spectrums of samples were computed by a confocal Raman microscope (Labram DILOR) equipped with an Olympus BX-41 microscope (objective ×100) and TEcooled CCD detector (Andor), in a back-scattering configuration using an He–He laser (532 nm excitation line) with power of 510 mW at a sample and spectral resolution of 0.8 cm−1. X-ray photoelectron spectra (XPS) over the samples were by captured Al-Kα radiation (1486.7 eV). Binding energies of Mn 2p and O 1s were calibrated using C 1s (BE = 285.0 eV) as a standard. The in situ FTIR experiments of NO adsorption over MnO x and Fe0.33Mn0.66O x catalysts were performed on a VERTEX70-FTIR. Prior to NO adsorption, the samples (approximately 20 mg each) was pretreated at 250 °C in the He atmosphere for 1 h. The spectrum of NO adsorption at different temperatures were selected over each catalyst. The reaction condition was controlled as follows: 500 ppm NO and He as balance, and the flow rate was 100 mL/min.

Microstructure Variation of Ni-YSZ by Infiltration Using Urea Precipitation Method and Their Electrochemical Properties

Impregnation or infiltration are terms used to describe the process of depositing nano particles into electrode structure. Using infiltration of nano particles, cell performance can be improved due to increased three phase boundary (TPB) where electrochemical reactions occur. So, by infiltration of dispersed particles, we can expect more performance due to increased surface area. But, many literatures related to infiltration for improving performance deal with almost air electrode infiltration. Commonly, Ni and electrolyte materials are used as fuel electrode. To infiltrate nano particles, fuel electrode needs appropriate porosity and maintains porous structure. But, it is hard for fuel side electrode to maintain its structure because Ni can be oxidized to NiO easily during heat treatments. So, not to be reoxidized, reduction of fuel electrode was done at the last process. And, one side reduction is necessary because air electrode can be decomposed in low pO2 condition. To infiltrate dispersed nano particles, we used urea precipitation method because it gives the solution precipitating ligands to whole solution so that precipitations occur homogeneously. Because urea needs decomposition time, urea concentration should be higher than cation concentration so as to precipitate whole cations. Thus, urea/cation concentration ratio and aging time were chosen as variables. Infiltration was conducted to Ni-YSZ support whose air electrode side was blocked by epoxy. After infiltration, epoxy was burned out at 600oC with fuel electrode flowed by H2. Finally, electrochemical properties were investigated by I-V curve, EIS and DRT.

Microstructure Variation of Ni-YSZ by Infiltration Using Urea Precipitation Method and Their Electrochemical Properties

Co-electrolysis of steam/CO2 for direct production of syngas (H2+CO) carried out through high temperature solid oxide electrolysis cells (SOEC) is an efficient and environmental-friendly approach for energy storage and reduce CO2 emission. In this study, Ni-yttria stabilized zirconia supported Ni-YSZ fuel electrode and La0.6Sr0.4Co0.2Fe0.8-GDC10 air electrode button cell have been fabricated and investigated in steam/CO2 co-electrolysis using different fuel compositions at 800°C. Furthermore, to improve the cell performance in co-electrolysis, 10% GDC nanoparticles were mono-dispersed on the Ni-YSZ electrode support using controlled urea/cation vapor infiltration method. The results show that the mono-dispersed 10% GDC nanoparticles deposited on entire electrode support matrix maintaining porous structure. When the co-electrolysis operated on infiltration cell with a stream of N2 63.5%, H2 5%, CO2 11.5% and H2O 20%, H2/CO ratio increased from 2.15% to 2.89% under the current density of 0.6 A/cm2 compared with the co-electrolysis operation of non-infiltrated cell.

Cobalt oxide synthesized using urea precipitation method as catalyst for the hydrolysis of sodium borohydride

In this study, we report a simple precipitation method for cobalt oxide (Co3O4) nanorods synthesis using cobalt chloride and urea in aqueous solution. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The characterization results indicate that urea is an attractive material that can be used as precipitation agent for preparing Co3O4 nanorods by controlling synthesis condition. The catalytic activity of as-prepared material was investigated for hydrolysis reaction of sodium borohydride and it is found that Co3O4 nanorods shows excellent hydrogen production in title reaction. After reaction course, Co3O4 nanorods can be recycled and reused without any apparent loss of activity which makes this process cost effective and hence ecofriendly.

Ultrafine Gd2O2S:Pr powders prepared via urea precipitation method using SO2/SO42 − as sulfuration agent—A comparative study

Nano-rods and tremelliform Gd2O2S:Pr powders were prepared via a urea precipitation method using SO2 and SO42− as sulfuration agent, respectively. Gd2O2S:Pr nano-rods with diameter of about 200nm were obtained while the scale of tremelliform Gd2O2S:Pr reaches tens of microns. Gd2O2S:Pr nano-rods exhibits better crystallinity and stronger luminescence intensity compared to that of tremelliform Gd2O2S:Pr. Intensive study on their formation process and mechanism is presented in this work. It is proposed that Gd2O2S:Pr nano-rods were obtained from Gd2(SO3)3·3H2O nano-rods synthesized via a dissolution-deposition process while tremelliform Gd2O2S:Pr is prepared via an oriented growth process using SO42− as sulfuration and regulation agent. As prepared Gd2O2S:Pr powders show strong green emission light at 512nm under excitation of 318nm ultraviolet light. Optimal concentration of Pr3+ is around 1mol% since it exhibits the highest luminescence intensity at that concentration. This study is extremely prospective for the preparation and morphology control of sulphide luminescent materials.

Evaluation of the physiochemical properties and catalytic performance of mixed metal oxides-carbon nanotubes nanohybrids containing carbon nanotubes with different diameters

In this study, three types of oxided multi-wall carbon nanotubes (o-MWCNT) with different diameters and oxygen-containing group content were used to synthesize Layered double hydroxides/mixed metal oxides-carbon nanotubes (LDH/MMO-CNT) nanohybrids via a homogeneous urea precipitation method. The surface morphology, structure, graphitization of as-prepared nanohybrids were investigated by Scanning electron microscopy, X-ray diffraction and Raman measurements, etc. The results showed that 3D hierarchical honeycomb nano-structured MMO-CNT was obtained when adding o-MWCNT with a diameter <8nm during preparation. And addition of o-MWCNT with a diameter >30nm; resulted in formation of a structure in which 1D CNT coupled with layers of 2D LDH/MMO with a “line-face” morphology. The results of bisphenol A degradation showed that addition of o-MWCNT with a smaller diameter led to better catalytic performance of MMO-CNT nanohybrids. It may be attributed to the better graphitization and highly dispersed activated components in the catalyst.

Reactive removal of 2-chloroethyl ethyl sulfide vapors under visible light irradiation by cerium oxide modified highly porous zirconium (hydr) oxide

Highly porous cerium oxide modified Zr(OH)4 samples were synthesized using a simple one stage urea precipitation method. The amorphicity level of zirconium hydroxide did not change upon addition of cerium oxide particles. A unique aspect of the cerium oxide-modified materials is the presence of both the oxide (CeO2) and hydroxide (Zr(OH)4) phases resulting in a unique microporous structure of the final material. Extensive characterization using various chemical and physical methods revealed significant differences in the surface features. All synthesized materials were microporous and small additions of cerium oxide affected the surface chemistry. These samples were found as effective catalysts for a decontamination of mustard gas surrogate, 2-chloroethyl ethyl sulfide (CEES). Cerium oxide addition significantly decreased the band gap of zirconium hydroxide. Ethyl vinyl sulfide and 1,2-bis (Ethyl thio) ethane were identified as surface reaction products.

Comparison of the Reactive Adsorption Desulfurization Performance of Ni/ZnO–Al2O3 Adsorbents Prepared by Different Methods

In this study, a series of Ni/ZnO–Al2O3 mixed oxide (MO) adsorbents were prepared by the one-step homogeneous precipitation method and the cation–anion double hydrolysis (CADH) method for reactive adsorption desulfurization (RADS) using thiophene as a model fuel in a fixed bed reactor. The synthesized adsorbents were characterized by N2 sorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), H2 temperature-programmed reduction (H2-TPR), ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy (DRS), and Raman spectroscopy. Results show that both Ni loading and the preparation method have a significant effect on the RADS activities of the adsorbent. Among the studied adsorbents, 10% Ni/ZnO–Al2O3 prepared by the one-step urea precipitation method showed the best RADS performance, with a thiophene conversion up to 96% and a sulfur adsorption capacity of 86 mg of S/g, which is 34% larger than that of CADH adsorbents. In addition, upon five RADS–regen...