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[Display omitted] • Utilizing Bacterial Cellulose as a Pore-Forming Agent to Synthesize Multi-Layered, Multi-Porous Composite Metal Oxide Catalysts. • Bacterial Cellulose Mitigates Environmental Risks and Cost in Catalyst Preparation. • In-Depth Analysis Reveals How the Pore Structure Created by Cellulose Pore-Forming Agent Enhances Catalytic Activity. Utilizing environmentally-friendly bacterial cellulose as a scaffold, a highly porous, layered OA-BC catalyst was synthesized through an enhanced sol-gel process. This catalyst demonstrated exceptional performance in the oxidation of toluene, outperforming conventional alternatives that utilize chemical porogens. The OA-BC catalyst efficiently degrades toluene at 220℃ with high stability and hydrophobicity, indicating resistance to deactivation. Its superior activity is due to increased oxygen vacancies, enhanced metal oxide cooperation, and a layered porous structure, which together enhance active oxygen species and oxygen diffusion. Calcination of the OA-BC catalyst results in molecular cleavage and formation of small aggregates, increasing hydroxyl groups that stabilize Cu and Ce centers, enhancing toluene-oxygen reactions. In-situ infrared and X-ray photoelectron spectroscopy confirm stable monodentate Cu+ ligands, contributing to its high catalytic activity. This study introduces a novel approach by employing bacterial cellulose as a template for synthesizing a porous stratified OA-BC catalyst, demonstrating superior performance in toluene oxidation. The efficacy of catalyst results from a tripartite synergy involving the stratified porous architecture, the stabilizing effect of Cu+-coordinating ligands and hydroxyl groups, and the interplay of hydroxyl electron donors and acceptors, shedding light on environmentally benign catalyst development. [ABSTRACT FROM AUTHOR]

The CuMn/ZSM-5 (CM/Z), CuMn/Beta (CM/B), and CuMn/SSZ-13 (CM/S) catalyst samples were prepared via an excess impregnation method to investigate the metal-support effect. The results show that the activity at 550 °C for NO direct decomposition follows the order of CM/Z (53.4%) > CM/B (49.2%) > CM/S (7.9%). The good activity and stability of CM/Z are attributed to a strong support effect including forming more active copper sites of the (Cu2+-O2--Cu2+)2+ and (Cu+-□-Cu+)2+ dimers, which have higher redox activity, capacity of oxygen mobility, and NO sorption capability. The competitive adsorption between NO and O 2 on the oxygen vacancy of dimers over CM/Z results in the activity decrease from 53.4% to 40.3% at 550 °C after adding 1 vol% O 2. The reaction mechanism over CM/Z was discussed based on the in situ DRIFT and isotopic (18O 2) experiments. Two NO adsorbs firstly on (Cu+-□-Cu+)2+ to form N 2 O, and N 2 O is activated to produce N 2 , followed by the NO adsorption on (Cu2+-O2--Cu2+)2+ to form nitrite and nitrate species and decomposition to NO and O 2. [Display omitted] ● The support effect of ZSM-5, Beta, and SSZ-13 supported CuMn is examined. ● CuMn/ZSM-5 exhibits a high NO to N 2 conversion of 53.4% at 550 °C. ● The intermediate species and competitive adsorption of NO and O 2 are discussed. ● The reaction pathways for NO direct decomposition are proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The controllable morphology synthesis of hexagonal WO 3 (HWO) was achieved by commercial bacterial cellulose (C). • The obtained V 2 O 5 /HWO-C catalyst exhibits effective resistance to K poisoning and SO 2 , and follows the Langmuir-Hinshelwood mechanism. • The detailed alkali metal-resistant pathways for the distribution of alkali metal ions (K+) on the K-V 2 O 5 /HWO-C catalyst were proposed. A series of V 2 O 5 /HWO catalysts are prepared by hydrothermal and impregnation methods using different precursors, among which the V 2 O 5 /HWO-C catalyst exhibited the optimal NH 3 -SCR performance. Compared to oxalic acid (O) and water (W), commercial bacterial cellulose (C) as a precursor can firstly achieve a more controllable synthesis to form hexagonal WO 3 (HWO) of V 2 O 5 /HWO-C catalyst. Various characterization (XRD, N 2 -BET, TEM, SEM, XPS, EDX mapping, and NH 3 /NO-TPD-MS) indicate that a higher specific surface area, abundant active oxygen and surface acidity result from the V 2 O 5 /HWO-C catalyst. The reason is that HWO-C has an excellent and smooth rod-shaped morphology, which promotes high dispersion of V 2 O 5 on its surface. In situ IR results show that the SCR follows the Langmuir-Hinshelwood (L-H) mechanism, where absorbed NO x intermediate species are formed on the V 2 O 5 and react with the NH 4 + and NH 3abs groups of V 2 O 5 and HWO. After loading 1.75 wt% K+, the obtained K-V 2 O 5 /HWO-C catalyst exhibits effective resistance to K poisoning and SO 2 , and retains 78 % NO x conversion efficiency at 360 °C after 10 h, attributed to the effective capture of K+ (1.04 wt%) in HWO-C channels via a new pathway, although approximately 0.71 wt% K+ are located on HWO-C external surface with weak bonding to V 2 O 5. [ABSTRACT FROM AUTHOR]

CO self-sustaining catalytic combustion tends to be one of potential means to achieve efficient conversion of off-gases from steelmaking. Building model catalysts to investigate the reaction process academically is essential to design optimized catalysts and Cu 2 O exposing (1 0 0), (1 1 1) and (1 1 0) planes are excellent materials. Herein, morphological CeO 2 /Cu 2 O inverse model catalysts were synthesized to reveal the synergistic effect and reaction mechanism. It is demonstrated that the ignition temperature is lowered on the interface by synergistic effect, which dominates the ignition, while the combustion after ignition is controlled by Cu 2 O planes providing abundant lattice oxygen to react with CO. Additionally, exposure of different planes plays a significant role in the reaction since O-termination on (1 0 0) inhibits the interaction, whereas Cu-termination on (1 1 0) surface structure and coordinately unsaturated Cu+ on open (1 1 1) surface respectively contribute to their superior catalytic performance. [Display omitted] ● Inverse model CeO 2 /Cu 2 O catalysts with regular morphology were successfully prepared. ● Synergistic effect on Cu-Ce interface lowered ignition temperature, dominating the ignition. ● The catalytic activity and synergistic effect vary among planes with (1 1 1) performing the best. ● Exposure of crystal planes with higher activity assists in designing optimized catalysts. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The catalytic self-sustained combustion of toluene was successfully developed. • CuCeZr/TiO 2 catalyst showed the excellent performance in self-sustained combustion. • TPO in N 2 atmosphere was used to investigate the role of lattice oxygen in toluene combustion. Abstract The catalytic self-sustained combustion of toluene over Cu x Mn 1-x Ce 0.75 Zr 0.25 /TiO 2 catalysts (x = 1, 0.5, 0) was studied in a microscale combustor. The catalytic activity is determined not only by the temperature with toluene conversion of 90% (T co), but also by the corresponding lean-combustion limits. It was found that the self-sustained combustion was achieved successfully over the catalysts, with the toluene concentrations of 0.35 con.%, 0.50 con.% and 1.00 con.%. According to T co, the activity decreased in the order of CuCe 0.75 Zr 0.25 /TiO 2 (234 °C)＞Cu 0.5 Mn 0.5 Ce 0.75 Zr 0.25 /TiO 2 (238 °C) ＞MnCe 0.75 Zr 0.25 /TiO 2 (284 °C). The excellent activity of CuCe 0.75 Zr 0.25 /TiO 2 catalyst could be ascribed to the high content of active lattice oxygen, good low-temperature reducibility and homogeneous dispersion, combined with the results of H 2 -TPR, O 2 -TPD and XPS. Furthermore, the results of in-situ DRIFT and temperature-programmed oxidation (TPO) of toluene in N 2 atmosphere suggested that toluene was adsorbed on the catalyst surface by removing α-H from methyl and combining with active oxygen specie to form benzyl group, which was finally oxidized into CO 2 and H 2 O with lattice oxygen. [ABSTRACT FROM AUTHOR]

• Ea of intermediate species is calculated during toluene oxidation. • Relationship between the activation energy of the overall and primitive reaction. • Transient response experiments of isotopically labeled oxygen. • M−K mechanism dominates in the oxidation of toluene. Catalytic properties of multiple metals deposited on TiO 2 nanoparticles were investigated in the oxidation of toluene. Isovolume impregnation method prepared the catalysts containing Cu, Mn, Ni, Co, and Fe deposited on TiO 2 , including CeO 2 and ZrO 2. The effects of loaded metal oxides on the structure and activity of initial catalysts were investigated using various characterization techniques. Toluene's removal efficiency and CO 2 selectivity in the catalyst system were classified as follows: CuCeZr/T > MnCeZr/T > NiCeZr/T > CoCeZr/T > FeCeZr/T. Presence of water vapor exhibits an inhibitory effect on the conversion of toluene, which diminishes at higher temperatures. One contribution of this paper is to obtain the oxidation pathway of toluene and the relationship between the activation energy of all-inclusive and elementary reactions based on the variation of infrared spectrum using Freeman-Carroll method. Another contribution is to clarify the share of Langmuir-Hinshelwood and Mars-van Krevelen mechanisms during the oxidation of toluene over CuCeZr/T catalyst by transient response experiments of isotopically labeled oxygen. These findings provide a feasible method for the design and synthesis of transition metal oxide catalysts for industrial applications. [ABSTRACT FROM AUTHOR]

Cubic Cu 2 O micro/nanocrystals were successfully synthesized by liquid-phase reduction using copper salt of CuSO 4 or CuCl 2 ·2H 2 O, and glucose or ascorbic acid as reducing agent, respectively. The activity of the catalysts was evaluated by light-off curves of CO self-sustained catalytic combustion via temperature-programmed oxidation of CO (CO-TPO), with the results showing the activity of catalysts following the order of Cu 2 O–Cl-GLU > Cu 2 O– S -GLU > Cu 2 O– S -AA > Cu 2 O–Cl-AA, (Cl denotes CuCl 2 ·2H 2 O, GLU denotes glucose, S denotes CuSO 4 and AA denotes ascorbic acid, respectively), corresponding to the ignition temperature of 109 °C, 122 °C, 137 °C and 186 °C, respectively. The crystal structure, elemental valence, morphology and redox property of the prepared catalysts were analyzed by using various characterization techniques. Combined with in situ infrared spectrum, the CO self-sustained catalytic combustion over Cu 2 O catalysts mainly follows the Mars-van-Krevelen (M-v-K) mechanism: the adsorbed and activated CO reacts with lattice oxygen to yield CO 2 and oxygen vacancy, and then the oxygen vacancy can be replenished by gaseous oxygen. Combined with catalytic performance of high-concentration CO, it is found that the catalysts prepared using glucose as reducing agent are more angular compared with ascorbic acid. The Cu 2 O–Cl-GLU synthesized with glucose and CuCl 2 ·2H 2 O exhibits the best catalytic activity among all the catalysts tested, attributing to its more obvious edge and rough crystal surface. The unique structure of Cu 2 O–Cl-GLU leads to the high exposure rate and coordination unsaturation of atoms on the cubic Cu 2 O micro/nanocrystals that can improve the ability of activating gaseous O 2 and low temperature reducibility, and consequently facilitating the catalytic activity. Cycle path diagram of CO oxidation reaction (a) and schematic diagram of CO oxidation reaction on Cu 2 O (b). [Display omitted] • Effects of reducing agent on catalytic properties is greater than that of copper salt. • High concentration CO can achieve self-sustained catalytic combustion on obtained Cu 2 O. • Glucose enhances unsaturation of Cu atoms contributing to high activity. • Chemically adsorbed oxygen on Cu 2 O surface promotes CO ignition. [ABSTRACT FROM AUTHOR]

• The LMO-W, LMO-SW, LCMO-W, LCMO-SW, LSMO-W and LSMO-SW catalysts were well designed by precursors. • The Binary search was used to determine the lean-combustion limits for the self-sustained combustion of CO. • The stability of the LCMO-SW catalyst was evaluated under CO oxidation at the furnace temperature of 535 °C. • The influence mechanism of self-sustaining combustion stability of CO catalyst was investigated and put forward. • The L-H mechanisms were performed for SCR reaction over the catalysts via in situ IR experiments. The LaMnO 3 , La 0.9 Ce 0.1 MnO 3 and La 0.9 Sr 0.1 MnO 3 catalysts are synthesized using sugar agent, and the CO self-sustained combustion is investigated, where the catalytic performance is decided by temperature with CO conversions of 10% (T 10), 50% (T 50), and 90% (T 90). The results show that self-sustaining combustion is successfully realized on the catalyst, and the order of activity decrease is as follows: La 0.9 Ce 0.1 MnO 3 (with sugar) > La 0.9 Sr 0.1 MnO 3 (with sugar) > LaMnO 3 (with sugar) > LaMnO 3 (without sugar) > La 0.9 Sr 0.1 MnO 3 (without sugar) > La 0.9 Ce 0.1 MnO 3 (without sugar). Combined with the results of XPS, H 2 -TPR, O 2 -TPD and CO-TPD techniques, the excellent activity of La 0.9 Ce 0.1 MnO 3 (with sugar) can be attributed to the high content of Mn4+ ions and reactive oxygen vacancies enriched on the catalyst surface, sound low-temperature reduction, and uniform dispersion. Besides, in situ IR spectroscopy results indicate that the catalytic combustion of CO over manganese-based perovskite catalysts follows the L-H mechanism: the chemisorption of CO and O 2 takes place to produce monodentate carbonates and bicarbonate species, which then decompose to yield CO 2 release. The high-temperature stability test provides evidence that the La 0.9 Ce 0.1 MnO 3 (with sugar) gives 100% CO conversion and that the activities remain almost unchanged after reaction for 12 h, where the temperature of catalyst bed reaches about 717 °C. The results obtained are helpful to accept this technology on efficient and clean energy utilization in iron and steel industry. [ABSTRACT FROM AUTHOR]

• The powder sample is well designed and coated on the HC tube to form CuCe 0.75 Zr 0.25 O δ /HC catalyst. • The transient changes and two-dimensional temperature region are obtained for CO self-combustion via CO-TPO + FLIR. • The various intermediate species and competitive adsorption of reactants on different active sites are evidenced. • The different pathways and roles of M-K and L-H mechanisms are proposed using in situ IR. A CuCe 0.75 Zr 0.25 O δ catalyst was prepared by the sol-gel method and successfully coated on honeycomb ceramic (HC) carrier. The activity of CuCe 0.75 Zr 0.25 O δ /HC was determined by the CO-TPO + FLIR, with the results performing that the critical condition for CO self-sustained combustion is 3 vol% CO + 3 vol% O 2 /N 2 at 0.5 L/min. As the CO concentration increases from 1 vol% CO to 3 vol% CO, the induction process (T 15) shifts to rapid ignition with a transient change for the CO oxidation reaction. The furnace temperature for CO self-sustained combustion decreases with increasing the CO and O 2 concentrations. Upon increasing the CO 2 concentration, however, furnace temperature is needed to increase and realize CO complete conversion. The thermal stability test combined with SEM + EDX results indicate that the CuCe 0.75 Zr 0.25 O δ /HC retains an excellent thermal stability after a 200 h, and the high-temperature region remains at 225 ± 1 °C during the CO self-combustion reaction. The activity of catalyst is reduced slightly after the 200 h test because of the carbon deposition on the catalyst surface, but such a slight deactivation can be eliminated by the air oxidation method. In situ IR results show a competitive adsorption of CO/O 2 and CO 2 on the Cu-Ce active sites, indicating that the addition of gaseous CO 2 performs an inhibition of CO oxidation. CO preferentially adsorbs linearly at Cu+ sites to form carbonyls that react with lattice oxygen to produce CO 2 to release, which can be ascribed to M-K mechanism. The L-H mechanism is less important, which involves the relatively weak reaction of adsorbed CO and adsorbed oxygen on the Cu-Ce active sites to form carbonate species. [ABSTRACT FROM AUTHOR]