NH3 Temperature-programmed Desorption Research Articles

Selective Hydrodeoxygenation of Lignin and Its Derivatives without Initial Reaction Pressure Using MOF-Derived Carbon-Supported Nickel Composites

In this study, Ni-metal–organic frameworks (MOFs) were used as precursors to obtain carbon-supported nickel composites (Ni@C) after calcination. The hydrodeoxygenation properties of the model compound and corncob lignin were investigated without an external hydrogenation source and initial pressure. Additionally, the effect of Ni@C on degradation of model compounds, corncob lignin, and benzyl phenyl ether (BPE) under different conditions was examined. The results showed that with isopropanol as the in situ hydrogen source, the conversion percentage of BPE was 90.2% and the yield of phenol was 88.3 wt % at 150 °C. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), NH3 temperature-programmed desorption (NH3-TPD), X-ray photoelectron spectroscopy (XPS), and thermogravimetry (TG), and the lignin and bio-oil were characterized by gas chromatography–mass spectrometry (GC–MS) and two-dimensional heteronuclear single quantum coherence (2D-HSQC). It was found that the Ni@C catalyst with well dispersion, high support rate, and rich acid sites was successfully synthesized. In the process of degradation, the C–O ether bond in the structure of lignin was successfully broken to generate the phenolic monomer, and the high-efficiency hydrodeoxygenation of lignin was realized under mild conditions.

Catalytic oxidation of soot by CeO2–ZrO2 catalysts: Role of Zr

Human health has been adversely affected by the soot particles in the exhaust of diesel engines. In this study, ceria-zirconia supported 1, 3, and 5 wt% zirconium (Zr) catalysts were prepared using the co-precipitation method and tested for soot combustion. The chemical and physical properties of catalysts were evaluated through NH3-temperature-programmed desorption (NH3-TPD), scanning electron microscopy (SEM), physisorption analysis, Raman spectroscopy, H2-temperature programmed reduction (H2-TPR), and X-ray diffraction (XRD). The catalytic activity of the catalysts for soot combustion was tested in loose contact through thermo-gravimetric analysis (TGA). Nitrogen and air atmosphere were used for the combustion of model soot. 3 and 5 wt% Zr/CeO2–ZrO2 showed higher soot oxidation than 1 wt% Zr/CeO2–ZrO2 in the nitrogen atmosphere, whereas percentage weight loss of model soot was high with 1 wt% Zr/CeO2–ZrO2 than 3 and 5 wt% Zr/CeO2–ZrO2.

Effect of Physicochemical Properties of Co and Mo Modified Natural Sourced Hierarchical ZSM-5 Zeolite Catalysts on Vanillin and Phenol Production from Diphenyl Ether

The conversion of lignocellulose biomass to value-added chemicals is challenging. In this paper, the conversion process of diphenyl ether (DPE) as a model lignin compound to phenol and vanillin compounds involved a bifunctional catalyst in reaching the simultaneous one-pot reaction in mild conditions with a high yield product. The catalysts used in this conversion are hierarchical ZSM-5 zeolites and their cobalt oxide and molybdenum oxide impregnated derivate. The ZSM-5 zeolites were synthesized using alternative precursors from natural resources, i.e., Indonesian natural zeolite and kaolin. The physicochemical properties of the catalysts were determined with various characterization methods, such as: X-ray Diffraction (XRD), Fourier Transform Infra Red (FT-IR), Scanning Electron Microscope - Energy Dispersive X-ray (SEM-EDX), X-ray Fluorescence (XRF), Surface Area Analyzer (SAA), and NH3-Temperature Programmed Desorption (NH3-TPD). The catalytic activity on conversion of DPE substrates showed that the MoOx/HZSM-5 produced the highest %yield for phenol and vanillin products; 31.96% at 250 °C and 7.63% at 200 °C, respectively. The correlation study between the physicochemical properties and the catalytic activity shows that the dominance of weak acid (>40%) and mesoporosity contribution (pore size of ~ 9 nm) play roles in giving the best catalytic activity at low temperatures. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Synthesis and characterization of mesoporous-HZSM-5 as a catalyst for ethanol dehydration to ethylene

In this work, mesoporous HZSM-5 (M-HZSM-5) was synthesized with γ-(2,3-epoxypropoxy) propyltrimethoxysilane as pore-expanding agent through one-pot method and was studied for its catalytic activity and stability in ethanol dehydration. The resultant samples were characterized by various techniques, including Brunauer-Emmett-Teller, Scanning electron microscopy, Fourier transform infrared spectroscopy, the temperature-programmed desorption of NH3, and Thermogravimetric. Based on the analysis of the results, M-HZSM-5 with the typical MFI structure displays a specific surface area of 450 m2 g−1. Furthermore, the improvement of the activity and anti-coking ability of the catalyst for ethanol dehydration to ethylene is attributed to the existence of mesopores in HZSM-5, which can provide the reaction space and acid sites.

Dispersion and Stabilization of Supported Layered Double Hydroxide-Based Nanocomposites on V-Based Catalysts for Nonoxidative Dehydrogenation of Isobutane to Isobutene

Nonoxidative dehydrogenation of isobutane is one of the sustainable strategies for producing high value added isobutene. As alternatives for the commercial Pt- and Cr-based dehydrogenation catalysts, supported V-based catalysts are worthy of study. In this work, a series of VOx/mMgAlO-R catalysts (m = 10, 15, 20, 25 and 30) were designed and prepared by loading VOx on mMgAlO composite oxide supports derived from mesoporous Al2O3-supported layered double hydroxide (LDH) nanocomposites. The calcined and reduced catalysts were characterized by X-ray diffraction (XRD), Raman spectra, Ultraviolet-visible diffuse reflectance (UV-Vis) spectra, NH3 temperature-programmed desorption (NH3-TPD), Temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG) and low temperature N2 adsorption–desorption isotherms. The as-synthesized VOx/20MgAlO-R with appropriate Mg addition exhibits superior activity (43–56% conversion and 77–81% selectivity), excellent stability and coking-resistance for the isobutane dehydrogenation. The structure–performance relationship reveals that the formation of VOx species confined in the reconstructed LDH interlayer and porous MgO facilitates dispersing and stabilizing the VOx species. The low polymerization degree and higher proportion of V4+ ion for VOx species, strong acidity of medium acid sites and low concentration of strong acid sites are responsible for the excellent anti-coking and catalytic performance. The strong VOx–support interaction is beneficial for enhancing the stability of the catalysts.

Micro-meso structure NaP zeolite @TiO2 nanocomposite: eco-friendly photocatalyst for simultaneous removal COD and degradation of methylene blue under solar irradiation.

A low-cost NaP zeolite@TiO2 nanocomposite catalyst with zeolite Si/Al ratio lower than three were synthesized for the first time under hydrothermal condition. The nanocomposites were characterized by different methods such as Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), N2 physisorption, NH3 temperature-programmed desorption (NH3-TPD), fluorescence microscopy, thermal analysis (TGA/DTA) and zeta potential analysis. The results showed that a micro-meso structure NaP zeolite with higher surface area and acidity with respect to pure zeolite was prepared. TiO2 nanoparticle was dispersed over the whole of zeolite without aggregation. A reduction of the TiO2 bandgap nanoparticle was observed from DRS spectra. The photocatalytic activity of low-cost NaP zeolite@TiO2 nanocomposite was tested for simultaneous methylene blue dye (MB) and chemical oxygen demand (COD) under solar and ultraviolet light. The result showed that the nanocomposite catalyst has great potential (above 90%) for COD removal discolouring of MB (about 99.6%) at room temperature. The optimum amount of some parameters such as the loaded amount of TiO2 (0.36g), catalyst dosage (0.1g), time (2h), initial dye concentration (100mg/L), solution pH value (about 7) under solar light were considered. In addition, present negative charge in the surface that show in zeta potential confirm the high activity of catalyst to interaction with cationic dye. As a further advantage, the NaP zeolite@TiO2 nanocomposite was easier to be separated in aqueous media than the pure TiO2 powders, making possible the reuse several times (over five runs) without using oxidant. Finally, the NaP zeolite@TiO2 nanocomposite was used for COD abatement in wastewater from two real industrial streams. The MB degradation kinetics were fitted by a pseudo-first-order model with K = 0.534h-1.

Hierarchical ZSM-5 zeolite obtained by designed organosiloxane: synthesis, characterization, and catalytic applications

A new strategy was implemented to synthesize hierarchical ZSM-5 zeolite, which uses self-made organosilanized double-terminal amino polyetheramine (ODAP) as a soft template to generate mesopores. The influence of the additional amount of ODAP on the textural properties and morphologies of the hierarchical ZSM-5 zeolite was investigated. The obtained hierarchical ZSM-5 zeolite was characterized by X-ray diffraction, N2 physical adsorption, SEM, temperature-programmed desorption of NH3, and other methods. The analysis of the experimental results shows that the maximum total BET specific surface area and mesoporous specific surface area of the optimized hierarchical ZSM-5 zeolite reached 609 and 278 m2/g, respectively. Because the synthesized hierarchical ZSM-5 zeolite has a large mesoporous specific surface area and abundant surface acidity, in terms of reactant conversion and product selectivity, compared with microporous zeolite, it exhibits excellent catalytic performance in the thiophene alkylation desulfurization reaction. This synthesis strategy can be extended to the preparation of zeolites with different framework structures, which is of great significance.

Promotional catalytic activity and reaction mechanism of Ag-modified Ce0.6Zr0.4O2 catalyst for catalytic oxidation of ammonia

Ce1-xZrxO2 composite oxides (molar, x = 0-1.0, interval of 0.2) were prepared by a cetyltrimethylammonium bromide-assisted precipitation method. The enhancement of silver-species modification and catalytic mechanism of adsorption-transformation-desorption process were investigated over the Ag-impregnated catalysts for low-temperature selective catalytic oxidation of ammonia (NH3-SCO). The optimal 5 wt.% Ag/Ce0.6Zr0.4O2 catalyst presented good NH3-SCO performance with >90% NH3 conversion at temperature (T) ≥ 250°C and 89% N2 selectivity. Despite the irregular block shape and underdeveloped specific surface area (∼60 m2/g), the naked and Ag-modified Ce0.6Zr0.4O2 solid solution still obtained highly dispersed distribution of surface elements analyzed by scanning electron microscope-energy dispersive spectrometer (SEM-EDS) (mapping), N2 adsorption-desorption test and X-ray diffraction (XRD). H2 temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS) results indicated that Ag-modification enhanced the mobility and activation of oxygen-species leading to a promotion on CeO2 reducibility and synergistic Ag0/Ag+ and Ce4+/Ce3+ redox cycles. Besides, Ag+/Ag2O clusters could facilitate the formation of surface oxygen vacancies that was beneficial to the adsorption and activation of ammonia. NH3-temperature programmed desorption (NH3-TPD) showed more adsorption-desorption capacity to ammonia were provided by physical, weak- and medium-strong acid sites. Diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments revealed the activation of ammonia might be the control step of NH3-SCO procedure, during which NH3 dehydrogenation derived from NHx-species and also internal selective catalytic reduction (i-SCR) reactions were proposed.

Effect of Indium Addition on the Low-Temperature Selective Catalytic Reduction of NO x by NH3 over MnCeO x Catalysts: The Promotion Effect and Mechanism.

A MnCeInOx catalyst was prepared by a coprecipitation method for denitrification of NH3-SCR (selective catalytic reduction). The catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry, scanning electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller analysis, H2 temperature-programmed reduction, and NH3 temperature-programmed desorption. The NH3-SCR activity and H2O and SO2 resistance of the catalysts were evaluated. The test results showed that the SCR and water resistance and sulfur resistance were good in the range of 125–225 °C. The calcination temperature of the Mn6Ce0.3In0.7Ox catalyst preparation was studied. The crystallization of the Mn6Ce0.3In0.7Ox catalyst was poor when calcined at 300 °C; however, the crystallization is excessive at a 500 °C calcination temperature. The influence of space velocity on the performance of the catalyst is great at 100–225 °C. FTIR test results showed that indium distribution on the surface of the catalyst reduced the content of sulfate on the surface, protected the acidic site of MnCe, and improved the sulfur resistance of the catalyst. The excellent performance of the Mn6Ce0.3In0.7Ox catalyst may be due to its high content of Mn4+, surface adsorbed oxygen species, high specific surface area, redox sites and acid sites on the surface, high turnover frequency, and low apparent activation energy.

Enhanced product quality through hydrodesulfurization of pyrolysis gasoline over a mixed metal oxide catalyst: An experimental and DFT study

Manipulating electronic properties of the hydrodesulfurization (HDS) catalysts can greatly impact the resulting product distribution. To address such effect decently in theoretical and experimental approaches, high-performance cobalt-molybdenum-supported alumina-titania (CoMo/Al2O3-TiO2) with different TiO2 loadings of 10–28 wt% were synthesized. The characterization of the catalysts was implemented by FE-SEM, TEM, XRD, BET/BJH (based on N2 adsorption–desorption), Fourier transform infrared spectroscopy (FTIR), H2-Temperature programmed reduction (H2-TPR), NH3-Temperature programmed desorption (NH3-TPD), and Thermal gravimetric analysis (TGA). The synthesized catalysts were evaluated through HDS of an industrial feedstock– pyrolysis gasoline (Pygas) in a pilot plant tubular fixed bed reactor. It was found that the modification of the electronic properties by titania could also increase the surface acidity while improving the reductive behavior of the tetrahedral and octahedral molybdenum species. In addition, the CoMo/Al2O3-TiO2 with 10 wt% titania content could excellently remove over 96% of sulfur-containing molecules in Pygas. Besides, the developed CoMo catalyst showed an increase in the aromatic compounds, resulting in improved product quality and value through the HDS process. Furthermore, the contribution of TiO2 to the synthesized catalyst was theoretically interpreted through the density functional theory (DFT) method. It was found that lower adsorption energy levels were estimated for the adsorption of the sulfur-bearing molecules on the CoMo/Al2O3-TiO2 than the CoMo/Al2O3 catalyst.

Effect of Steam Treatment on the Properties of Mordenite and Its Catalytic Performance in a DME Carbonylation Reaction

A series of dealuminated mordenite (MOR) samples with different acidities and various porosities were prepared through steam treatment of H+/Na+ mordenite. The obtained zeolites were elaborately characterized by X-ray diffraction, N2 adsorption–desorption, scanning electron microscopy, 29Si nuclear magnetic resonance (NMR), 27Al NMR, NH3 temperature-programmed desorption, and Fourier transform infrared spectroscopy, and the catalytic performance for dimethyl ether (DME) carbonylation was investigated. The characterization results revealed that the kind of cation balancing the zeolite charge had a great effect on the crystalline structure and acidity of mordenite zeolite during steam treatment and ion-exchange processes. Dealumination was observed both on Na-MOR and H-MOR, but it was much milder on the Na-MOR zeolite comparatively. After Na-MOR was treated with steam, its structure was well-preserved, but side pockets of mordenite were opened, resulting in an increased microporous volume and strong acid sites. Interestingly, it was found that the removal of framework Al in the 12MR channel was favored over the 8MR channel during steaming of Na-MOR, leading to the mordenite to possess more acid sites in the 8MR channel compared with those in the 12MR channel. As for the steamed H-MOR, both the crystalline structure and porosity were obviously damaged, resulting in a decreased microporous volume and acidity. The influence was more significant in the 8MR channel of H-MOR due to the obvious removal of framework Al and blockage of side pockets. The performance tests revealed that Na-MOR treated with steam was an effective way to enhance the catalytic performance for DME carbonylation reaction. The N-773 catalyst (steamed with Na-MOR at 773 K) showed a methyl acetate product rate of 0.33 gg–1 h–1, which was much higher than that of the parent H-MOR (0.23 gg–1 h–1). Moreover, the dealuminated catalyst exhibited a slow deactivation rate, which was possibly ascribed to the reduced strong acid sites in the 12MR channels. Although the steam treatment of H-MOR resulted in a lower activity in the DME carbonylation reaction, it exhibited a higher MeOAc selectivity and improved stability for its overall decreased acidity.

Selective Photocatalytic Activation of Ethanol C-H and O-H Bonds over Multi-Au@SiO2/TiO2: Role of Catalyst Surface Structure and Reaction Kinetics.

The chemical bond diversity and flexible reactivity of biomass-derived ethanol make it a vital feedstock for the production of value-added chemicals but result in low conversion selectivity. Herein, composite catalysts comprising SiO2-coated single- or multiparticle Au cores hybridized with TiO2 nanoparticles (mono- or multi-Au@SiO2/TiO2, respectively) were fabricated via electrostatic self-assembly. The C-H and O-H bonds of ethanol were selectively activated (by SiO2 and TiO2, respectively) under irradiation to form CH3CH•(OH) or CH3CH2O• radicals, respectively. The formation and depletion kinetics of these radicals was analyzed by electron spin resonance to reveal marked differences between mono- and multi-Au@SiO2/TiO2. Consequently, the selectivity of these catalysts for 1,1-diethoxyethane after 6 h irradiation was determined as 81 and 99%, respectively, which was attributed to the more pronounced effect of localized surface plasmon resonance for multi-Au@SiO2/TiO2. Notably, only acetaldehyde was formed on a Au/TiO2 catalyst without a SiO2 shell. Fourier transform infrared (FTIR) spectroscopy indicated that the C-H adsorption of ethanol was enhanced in the case of multi-Au@SiO2/TiO2, while NH3 temperature-programmed desorption and pyridine adsorption FTIR spectroscopy revealed that multi-Au@SiO2/TiO2 exhibited enhanced surface acidity. Collectively, the results of experimental and theoretical analyses indicated that the adsorption of acetaldehyde on multi-Au@SiO2/TiO2 was stronger than that on Au/TiO2, which resulted in the oxidative coupling of ethanol to afford 1,1-diethoxyethane on the former and the dehydrogenation of ethanol to acetaldehyde on the latter.

Manganese oxide nanorod catalysts for low-temperature selective catalytic reduction of NO with NH3.

MnOx nanorod catalysts were successfully synthesized by two different preparation methods using porous SiO2 nanorods as the template and investigated for the low-temperature selective catalytic reduction (SCR) of NO with NH3. The catalysts were characterized by scanning electron microscopy, transmission electron microscopy, nitrogen adsorption, X-ray diffraction, X-ray photoelectron spectroscopy, and NH3 temperature-programmed desorption. The results show that the obtained MnOx-P nanorod catalyst prepared by redox precipitation method exhibits higher NO removal activity than that prepared by the solvent evaporation method in the low temperature range of 100–180 °C, where about 98% NO conversion is achieved over MnOx(0.36)-P nanorods. The reason is mainly attributed to MnOx(0.36)-P nanorods possessing unique flower-like morphology and mesoporous structures with high pore volume, which facilitates the exposure of more active sites of MnOx and the adsorption of reactant gas molecules. Furthermore, there is a lower crystallinity of MnOx, higher percentage of Mn4+ species and a large amount of strong acid sites on the surface. These factors contribute to the excellent low-temperature SCR activity of MnOx(0.36)-P nanorods.

Insight into the role of PEG on Mo-Bi based catalyst in isobutene selective oxidation to methacrolein

Mo-Bi based catalyst has been synthesized by PEG-assisted hydrothermal method, and tested in selective oxidation of isobutene to methacrolein (MAL). It is found that the catalysts assisted by PEG exhibited higher selectivity and yield of MAL in oxidation of isobutene. To investigate the role of PEG on Mo-Bi based catalyst, a series of MoBiFeCoCeCs mixed oxide catalysts were prepared by PEG-assisted hydrothermal method. By combining the characterization of Mo-Bi based catalyst obtained by using X-ray diffraction (XRD) patterns, N2 physisorption measurements, Fourier transform infrared spectroscopy (FT-IR), NH3 temperature-programmed desorption (NH3-TPD) measurements, X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF) spectroscopy and scanning electron microscope (SEM), it was verified that the assistance of PEG could change metal composition and states, inhibit agglomeration of particles and adjust acidity of catalyst. Our finding may suggest the relationship of selective oxidation of isobutene with Mo-Bi based catalysts.

Effects of several ionic liquids on the structures and catalytic properties of double metal cyanides

A key challenge in the synthesis of catalyst is how to increase the catalytic property. Here Co(II)Fe(III) double metal cyanide (Co(II)Fe(III) DMC) had been prepared in presence with several typical kinds of ionic liquids(ILs), which were the ionic liquids with fluoroborate, fluorophosphate or -CF3, respectively. It is noteworthy that these ILs have shown significant influence on the catalytic performance of DMC for the epoxidation of styrene, and the Co(II)Fe(III) DMC catalyst modified with 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM]TF2N) show the highest catalytic efficiency. Then a series of techniques including infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), Thermogravimetric analysis (TGA), NH3-temperature programmed desorption (NH3-TPD), N2 adsorption–desorption measurement and X-ray absorption fine structure measurements(XAFS) have been used to explore the structures of Co(II)Fe(III) DMC + [BMIM]TF2N, respectively. Additionally, to further understand the influence of ionic liquid modifier, the mechanisms of the epoxidation of styrene with Co(II)Fe(III) DMC and Co(II)Fe(III) DMC + [BMIM]TF2N were probed by the density functional theory (DFT) based on the cluster model, respectively, unraveling the internal reason for the promotion of the catalyst performance. This understanding is critical to pave the way toward the design and preparation for novel catalysts.

N-Heptane isomerization activities of Pt catalyst supported on micro/mesoporous composites

Pt loaded on a series of MCM-48 silica and composites with HZSM-5 zeolite, HY zeolite, or TiO2 has been prepared and studied for n-heptane isomerization reaction at 200–350 °C. The structural characterization, acid distribution, and morphology of these catalysts were characterized by X-ray diffraction, Fourier transform infrared, UV–Vis diffuse reflectance, scanning electron microscope, temperature-programmed desorption of NH3, and nitrogen adsorption–desorption methods. The results show that these catalysts have a good selectivity to multi branched isomers, while producing low aromatic compounds. Also, these new composite catalysts prove the catalytic stability during the time of reaction. The most desirable results, and significantly higher n-heptane conversion and isomerization selectivity were achieved with Pt/MCM48-HZSM5 catalyst.

Analysis of NH3 -TPD Profiles for CuSSZ-13 SCR Catalyst of Controlled Al Distribution - Complexity Resolved by First Principles Thermodynamics of NH3 Desorption, IR and EPR Insight into Cu Speciation*.

NH3 temperature-programmed desorption (NH3 -TPD) is frequently used for probing the nature of the active sites in CuSSZ-13 zeolite for selective catalytic reduction (SCR) of NOx . Herein, we propose an interpretation of NH3 -TPD results, which takes into account the temperature-induced dynamics of NH3 interaction with the active centers. It is based on a comprehensive DFT/GGA+D and first-principles thermodynamic (FPT) modeling of NH3 adsorption on single Cu2+ , Cu+ , [CuOH]+ centers, dimeric [Cu-O-Cu]2+ , [Cu-O2 2- -Cu]2 species, segregated CuO nanocrystals and Brønsted acid sites (BAS). Theoretical TPD profiles are compared with the experimental data measured for samples of various Si/Al ratios and distribution of Al within the zeolite framework. Copper reduction, its relocation, followed by the intrazeolite olation/oxolation processes, which are concomitant with NH3 desorption, were revealed by electron paramagnetic resonance (EPR) and IR. DFT/FPT results show that the peaks in the desorption profiles cannot be assigned univocally to the particular Cu and BAS centers, since the observed low-, medium- and high-temperature desorption bands have contributions coming from several species, which dynamically change their speciation and redox states during NH3 -TPD experiment. Thus, a rigorous interpretation of the NH3 -TPD profiles of CuSSZ-13 in terms of the strength and concentration of the active centers of a particular type is problematic. Nonetheless, useful connections for molecular interpretation of TPD profiles can be established between the individual component peaks and the corresponding ensembles of the adsorption centers.

The synthesis of zirconium and tetraethylenepentamine bi-functionalized TiO2 for efficient CO2 adsorption

In the present work, zirconium-doped metal oxide of TiO2(ZrN) was synthesized and functionalized with different amount of tetraethylenepentamine (TEPA). The physical properties of the materials were tested using temperature-programmed desorption of NH3, X-ray diffractometer, X-ray photoelectron spectrometer, scanning electron microscope, transmission electron microscope, energy dispersion spectrum, Inductively coupled plasma atomic emission spectroscopy, Infrared spectrometer, N2 adsorption-desorption analyzer, energy dispersion spectrum and thermogravimetric analyzer. Zr species has a positive effect on the enhancement of the thermal stability and amine utilization. After the introduction of Zr, the decomposition temperature of TEPA is improved to 180℃. Over TEPA decorated adsorbents, physical adsorption and chemical adsorption occurs simultaneously. When the adsorption time is 75℃, CO2 flow rate is 20 mL/min, the adsorbent of TEPA(40)/TiO2(Zr0.1) exhibit a remarkable amine utilization of 83.5%.

Screening of Adsorbent/Catalyst Composite Monoliths for Carbon Capture-Utilization and Ethylene Production.

Combining CO2 adsorption and utilization in oxidative dehydrogenation of ethane (ODHE) into a single bed is an exciting way of converting a harmful greenhouse gas into marketable commodity chemicals while reducing energy requirements from two-bed processes. However, novel materials should be developed for this purpose because most adsorbents are incapable of capturing CO2 at the temperatures required for ODHE reactions. Some progress has been made in this area; however, previously reported dual-functional materials (DFMs) have always been powdered-state composites and no efforts have been made toward forming these materials into practical contactors. In this study, we report the first-generation of structured DFM adsorbent/catalyst monoliths for combined CO2 capture and ODHE utilization. Specifically, we formulated M-CaO/ZSM-5 monoliths (M = In, Ce, Cr, or Mo oxides) by 3D-printing inks with CaCO3 (CaO precursor), insoluble metal oxides, and ZSM-5. The physiochemical properties of the monoliths were vigorously characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 physisorption, elemental mapping, pyridine Fourier transform infrared spectroscopy (Py-FTIR), H2-temperature-programmed reduction (H2-TPR), and NH3-temperature-programmed desorption (NH3-TPD). Their performances for combined CO2 adsorption at 600 °C and ODHE reaction at 700 °C under 25 mL/min of 7% C2H6 were then investigated. The combined adsorption/catalysis experiments revealed the best performance in Cr-CaO/ZSM-5, which achieved 56% CO2 conversion, 91.2% C2H4 selectivity, and 33.8% C2H4 yield. This exceptional performance, which was improved from powdered-state DFMs, was attributed to the high acidity and numerous oxidation states of the Cr2O3 dopant which were verified by NH3-TPD and H2-TPR. Overall, this study reports the first-ever proof-of-concept for 3D-printed DFM adsorbent/catalyst materials and furthers the area of CO2 capture and ODHE utilization by providing a simple pathway to structure these composites.

Oxidative Desulfurization of Tire Pyrolysis Oil over Molybdenum Heteropolyacid Loaded Mesoporous Catalysts

Pyrolysis oil derived from waste tires consists of sulfur content in the range of 7000 to 9000 ppm. For use in diesel engines, its sulfur content must be lowered to 10 to 15 ppm. Though conventional hydrodesulfurization is suitable for the removal of sulfur from tire pyrolysis oil, its high cost provides an avenue for alternative desulfurization technologies to be explored. In this study, oxidative desulfurization (ODS), a low-cost technology, was explored for the desulfurization of tire pyrolysis oil. Two categories of titanium-incorporated mesoporous supports with 20 wt% loaded heteropoly molybdic acid catalyst (HPMo/Ti-Al2O3 and HPMo/Ti-TUD-1) were developed and tested for ODS of tire pyrolysis oil at mild process conditions. Catalysts were characterized by X-ray diffraction, BET-N2 physisorption, and X-ray photoelectron spectroscopy (XPS). The incorporation of Ti into Al2O3 and TUD-1 frameworks was confirmed by XPS. The surface acidity of catalysts was studied by the temperature-programmed desorption of NH3 and pyridine FTIR analyses. HPMo/Ti-Al2O3 and HPMo/Ti-TUD-1 catalysts contained both Lewis and Brønsted acid sites. The presence of titanium in catalysts was found to promote the ODS activity of phosphomolybdic acid. The Ti-TUD-1-supported catalysts performed better than the Ti-Al2O3-supported catalysts for the ODS of tire pyrolysis oil. Hydrogen peroxide and cumene peroxide were found to be better oxidants than tert-butyl hydroperoxide for oxidizing sulfur compounds of tire pyrolysis oil. Process parameter optimization by the design of experiments was conducted with an optimal catalyst along with the catalyst regeneration study. An ANOVA statistical analysis demonstrated that the oxidant/sulfur and catalyst/oil ratios were more significant than the reaction temperature for the ODS of tire pyrolysis oil. It followed the pseudo-first-order kinetics over HPMo/Ti-TUD-1.