High-temperature Hydrothermal Treatment Research Articles

In-situ formed stable Pt nanoclusters on ceria-zirconia solid solutions induced by hydrothermal aging for efficient low-temperature CO oxidation

Pt nanoclusters (PtC) on the surface of ceria-zirconia solid solutions exhibit superior low-temperature CO oxidation activity compared to Pt single atoms (Pt1). However, the redispersion behavior of the PtC to Pt1 lowers the efficiency of CO Oxidation. In this work, the stable surface hydroxyl groups were constructed by high-temperature hydrothermal aging treatment. Specifically, the Pt1 catalyst (Pt/CZOe-SA) prepared by atom trapping was subjected to high-temperature hydrothermal treatment to obtain the stable PtC catalyst (Pt/CZOe-HT) with in-situ formed PtC. The experimental results showed that PtC with 2–3 nm size could achieve excellent low-temperature activity and thermal stability. In addition, the ab initio molecular dynamics and density functional theory calculations revealed the specific evolution process of dynamic dispersion for PtC with or without hydroxyl groups from the femtosecond scale, suggesting that the hydroxyl groups limited the dispersion of PtC in the form of “energy fence”. The hydrothermal treatment not only introduced high-temperature stable hydroxyl groups to improve the stability of the in-situ formed PtC, but also optimized the ratio of Pt1 and PtC, and then enhanced the low-temperature activity by the synergistic effect between Pt1 and PtC. The present work can provide theoretical guidance for developing high-performance and high-stability Pt-based catalysts.

Role of acidic hydrochar on dechlorination of waste PVC in high temperature hydrothermal treatment and fuel properties enhancement of solid residues

In this study, the chlorine mitigation from waste polyvinyl chloride (WPVC) during high temperature co-hydrothermal treatment (co-HTT) and the properties of the generated solid products were assessed. WPVC was co-fed with acidic hydrochar (AHC), which was produced via hydrothermal carbonization of pineapple waste in the presence of citric acid water solution. High temperature co-HTT experiments were performed at 300–350 °C, 0.25–4 h of reaction time, and 0–20 wt% AHC loading. Co-HTT solid products (co-HTT_SP) were characterized via proximate analysis, ultimate analyses, combustion analysis, and ash analysis. The results show that the addition of 5% AHC enhances the dechlorination efficiency (DE) of WPVC from 89.35% to 97.66% at 325 °C and 0.5 h. The highest DE, reaching 99.46%, was achieved at 350 °C and 1 h in the presence of 5 wt% AHC. Furthermore, loading 5% AHC improved the higher heat value (HHV) of the solid products from 23.09 to 31.25 MJ/kg at 325 °C and 0.5 h. The maximum HHV (34.77 MJ/kg) of a solid product was achieved at 350 °C, 4 h, in the presence of 5 wt% of AHC. The co-HTT solids shown low slagging indices, fouling indices, alkali indices, and medium chlorine contents. These findings support the viability of WPVC conversion into clean solid fuel via co-HTT.

Solid-state NMR study on dealumination mechanism of H-MOR zeolite by high-temperature hydrothermal treatment

The acidity of zeolites which plays an important role in various catalytic reactions is closely related to framework aluminum. After dealumination, not only the Si/Al ratio of zeolites increases, but also new aluminum species are generated. Furthermore, the pore structure and catalytic performance of zeolites are affected. High-temperature hydrothermal treatment, as a frequently-used method of dealumination, is widely concerned. However, the dealumination mechanism of zeolite during the hydrothermal treatment is not clear. In this work, the existence of different Al species in H-MOR during the process of high-temperature hydrothermal treatment was confirmed by 27Al MQ MAS NMR. It was found that the second tetrahedrally coordinated framework aluminum (Al(IV)-2) species is the precursor of amorphous non-framework aluminum transformed from framework aluminum of H-MOR during high-temperature hydrothermal treatment. Besides, the 1H-1H DQ-SQ NMR was used to study spatial proximity between different hydroxyl species. Finally, the dealumination process of H-MOR zeolite is revealed: Al(IV)-1 species firstly transformed into Al(IV)-2 species, and then evolved into pentahedrally coordinated aluminum (Al(V)) species and hexahedrally coordinated aluminum (Al(VI)) species.

Designing novel 0D/1D/2D NiO@La(OH)3/g-C3N4 heterojunction for enhanced photocatalytic hydrogen production

Structure design of heterojunction photocatalysts is highly desirable for making full use abilities of each component and junction. Herein, we designed a one-pot in-situ top-down and bottom-up combination strategy to construct novel 0D/1D ordered NiO@La(OH)3 heterostructure derived from NiO@LaNiO3 using high-temperature hydrothermal treatment. The 0D/1D NiO@La(OH)3 heterostructure had better charge transport capability than its single component and the corresponding mechanical mixture. Furthermore, NiO@La(OH)3 and g-C3N4 self-assembled into 0D/1D/2D NiO@La(OH)3/g-C3N4 ternary hierarchical heterostructure photocatalyst by electrostatic interaction. The synergistic effect of 0D/1D/2D architecture and ternary heterojunction boost the internal separation and interface transmission of its photocarriers. Therefore, the obtained 0D/1D/2D NiO@La(OH)3/g-C3N4 ternary photocatalyst exhibited significantly enhanced photocatalytic H2 evolution activity, comparable to related g-C3N4-based photocatalysts. This work enriches our insight into designing novel hierarchical heterostructure catalysts.

Effects of aging and hydrothermal treatment on the crystallization of ZSM-5 zeolite synthesis from bentonite.

In the present study, Lam Dong bentonite clay was utilized as a novel resource to effectively synthesize microporous ZSM-5 zeolite (Si/Al ∼ 40). The effects of aging and hydrothermal treatment on the crystallization of ZSM-5 were carefully investigated. Herein, the aging temperatures of RT, 60, and 80 °C at time intervals of 12, 36, and 60 h, followed by high temperature hydrothermal treatment (170 °C) for 3-18 h were studied. Techniques such as XRD, SEM-EDX, FTIR, TGA-DSC, and BET-BJH were applied to characterize the synthesized ZSM-5. Bentonite clay showed great benefits as a natural resource for ZSM-5 synthesis and is cost efficient, environment friendly, and has a large reserves. The form, size, and crystallinity of ZSM-5 were greatly influenced by aging and hydrothermal treatment conditions. The optimal ZSM-5 product had high purity, crystallinity (∼90%), and porosity (BET ∼380 m2 g-1) as well as thermal stability, which are beneficial for adsorptive and catalytic applications.

Calcination-free nanoarchitectonics of mesoporous conducting polymer@silica hybrids with ultra-large pores and their enhanced protein adsorption capacity

The nanohybrids of mesoporous conducting polymer@silica with ultra-large pore size are successfully in-situ synthesised from 3,4-propylenedioxythiophene (ProDOT) derived cationic surfactant and silica precursor assisted by co-solvent n-butanol at high temperature without any template removal process. The ultra-large mesopores pores are created in the nanohybrids without calcination step through an integrated approach of simple polymerisation and rearrangement of the conducting and hydrophobic monomeric unit, ProDOT unit followed by the pore swelling with the co-solvent and high-temperature hydrothermal treatment. By controlling the hydrothermal temperature and the amount of co-solvent, the pore size can be expanded from 11.6 nm to 27 nm. The prepared nanohybrid with ultra large pores exhibits a high adsorption capacity for large-sized protein (bovine serum albumin, BSA), and the adsorption capacity can be controlled with the adjustment of the pore size. The adsorption capacity of a nanohybrid with 27 nm is 166 mg/g, which is almost twice that of a nanohybrid with 11.6 nm (75 mg/g). The mesoporous conducting polymer@silica nanohybrids can be applied as a carrier for protein delivery or the support for enzymatic catalysis or biosensors.

Tuning hydrophobicity of HY zeolite by suppressing dealumination process for toluene adsorption in humid conditions

HY zeolites are widely used as adsorbent for volatile organic compounds removal due to their acceptable stability and high specific surface area. However, low adsorption capacity of toluene over HY zeolites at humid conditions limits their industrial application. In present work, the hydrophobicity of HY zeolite modified by CeO2 was enhanced successfully via a two-step process of high-temperature hydrothermal treatment and then acid treatment. It can be found that CeO2 introduction can significantly increase the adsorption capacity of toluene over HY zeolites. Typically, HY with 2 wt% CeO2 (2CeO2/HY-del) presented a remarkable adsorption amount of toluene (166.3 mg/gcat) and a satisfied regeneration performance at humid environment, which was higher than those of most reported modified Y zeolites (about 148.5 mg/gcat). The suppression of dealumination and maintaining of specific surface area during the harsh two-step treatment could be mainly responsible for the appropriate toluene adsorption capacity over the HY zeolites. Additionally, dynamic adsorption analysis revealed that the adsorption process belonged to the first-order adsorption kinetics, indicating that the adsorption process was mainly defined as a physical process. This work would guide the development of high toluene adsorption capacity at humid conditions.

Effect of High-Temperature Hydrothermal Treatment on the Cellulose Derived from the Buxus Plant.

Cellulose has attracted considerable attention as the most promising potential candidate raw material for the production of bio-based polymeric materials. In the last decade, significant progress has been made in the production of biopolymers based on different cellulose forms. In this study, cellulose was obtained in an innovative and environmentally friendly way, using boxwood powder. Crude cellulose was obtained by treating Buxus powder with an ethanol–acetic acid–water mixture. Refined cellulose was then obtained by treatment with an acidic sodium hypochlorite solution and alkaline hydrogen peroxide solution. The novel chemistry of cellulose prepared by this method promises to be not only green, but also highly desirable, because of its lower emissions and low cost. It is crucial for the future of the global polymer industry. The refined cellulose was subjected to a high-temperature hydrothermal treatment under two temperatures and time conditions, with temperature gradients of 120, 140, and 160 °C, and time gradients of 1, 2, and 3 h. The samples were subjected to infrared and thermogravimetric analyses. The cellulose undergoes dehydration and thermal degradation reactions during the heat treatment process, and the thermal stability of the residual is enhanced, compared with that of virgin cellulose. Between 120 and 140 °C, the hydroxyl and hypomethyl groups on the surface of cellulose are shed. Groups in the amorphous region of the polymer are the first to be shed. The dehydration reaction reduces the number of free hydroxyl groups on the surface of the cellulose molecules. The dehydration reaction was accelerated by an increase in temperature. Between 140 and 160 °C, the β-(1,4)-glycosidic bond begins to slowly break and some furans are generated. The structure of cellulose undergoes reorganization during thermal treatment. The thermal stability of the modified material is greater than that of untreated cellulose.

Effect of High-Temperature Hydrothermal Treatment on Chemical, Mechanical, Physical, and Surface Properties of Moso Bamboo

Bamboo is an ideal material as it is green, fast-growing, and easy to process. However, the low dimensional stability may limit the application of bamboo due to its richness in hydrophilic groups. Thus, an effective and environment-friendly modification is needed to solve the aforementioned problems. This study employed high-temperature hydrothermal treatment for the modification of bamboo to offer technical support to further promote the application of bamboo materials. Bamboo was heated at various temperatures (120–160 °C) for diverse durations (60–120 min), and the chemical composition, mechanical properties, dimensional stability, and surface color were studied. Results revealed that the parenchyma cells of bamboo were deformed and the parenchymal cell lumen without starch granules after treatment at 160 °C for 120 min. The cellulose and hemicellulose content of bamboo decreased, and the lignin content increased in relative terms as the temperature and time of high-temperature hydrothermal treatment continued to rise. The mechanical properties of bamboo declined after high temperature hydrothermal treatment, and the modulus of rupture (MOR) and modulus of elasticity (MOE) of bamboo at 160 °C for 120 min decreased by 47.11% and 16.14%, respectively, compared to untreated bamboo. The swelling test indicated that the dimensional stability of the bamboo was improved, and the swelling ratio of the bamboo was reduced through the high-temperature hydrothermal treatment. The tangential and radial swelling coefficients of bamboo were reduced by 53.28% and 53.59%, respectively, after treatment at 160 °C for 120 min compared to untreated bamboo. The bamboo surface color was darkened after heat treatment, which gives the bamboo better surface decorative properties.

Rapid high-temperature hydrothermal post treatment on graphitic carbon nitride for enhanced photocatalytic H2 evolution

Hydrothermal treatment has been widely employed for material synthesis and modification. In this work, with the help of the homemade microreactor, a rapid high-temperature hydrothermal post treatment (RHTHTPT) process with fast heat transfer and short processing time was elaborately designed for graphitic carbon nitride (g-C3N4). Taking advantage of high temperature and short duration time during RHTHTPT process, the RHTHTPT-derived g-C3N4 reached up to a high product yield over 80%. The RHTHTPT-derived g-C3N4 showed an enhanced photocatalytic H2-evolution activity about 5.1 times that of pristine g-C3N4 under visible-light irradiation (λ > 400 nm). With systematic characterizations and the tracking of gas-liquid-solid products by RHTHTPT, it was found that the RHTHTPT could effectively enlarge the specific surface area to increase the active sites for photocatalytic H2-evolution reaction, abundant amino groups and the insertion of oxygen-containing functional groups in the surface of g-C3N4 could realize efficient carriers separation, both of which gave rise to the improved photocatalytic H2-evolution performance. This work develops a promising hydrothermal strategy to regulate the in-plane structure of g-C3N4 and brings a deeper understanding for the correlation between RHTHTPT-induced structure modification with photocatalytic ability, and therefore further provides some guidelines for directionally designing the special structures of g-C3N4 as well as other potential materials by hydrothermal modification.

Recovery of red iron oxide pigment from zinc plant hematite precipitates

ABSTRACT Hematite precipitates during zinc hydrometallurgy contain a certain amount of Zn and S impurities, which limit its applications. To remove these impurities and prepare high-value red iron oxide, a two-part study was carried out by atmospheric water washing and high-temperature hydrothermal treatment. The results showed that Zn2+ and SO4 2− existed two forms: adsorbed on the surfaces of hematite precipitates and via physical inclusions; as insoluble sulfates, jarosite, and basic ferric sulfate. During the high-temperature hydrothermal reactions (240°C, 6h, 10g/L H2SO4, 6 mL/g liquid-to-solid ratio), the non-iron phases in hematite precipitates transformed into iron oxides. The iron content in the product increased from 58.7% to 68.8%, the sulfur content decreased from 2.96% to 0.63%, and the zinc content decreased from 1.03% to 0.07%. The specific surface area increased from 0.39m2/g to 1.44 m2/g. These products met the application requirements of ISO 1248-C-II-2-a for red iron oxide.

Carbon Cloth Modified Electrode for the Rapid PB Detection in Water

Through simple high-temperature hydrothermal treatment of carbon cloth, a hoCCE electrochemical sensor wasprepared for detecting Pb2+. After hydrothermal treatment, the carbon cloth surface has more ketone-based sitesand defects, which improves the electrochemical active area, conductivity and detection sensitivity, andstrengthens the catalytic performance of Pb2+. Under optimal conditions, the current concentration curve wasobtained by differential pulse anodic stripping voltammetry, with linear range 0.06 - 1.6 μM, regression equationIp(mA) = 0.03208 + 0.12843C (μM), and detection limit 30 nM. The resulting sensor was applied to detect Pb2+ inreal-life water samples. Compared with other studies, hoCCE enjoys advantages in linear interval detection, cost,preparation procedure, and vulnerability.

Grain size effect on the high-temperature hydrothermal stability of Cu/SAPO-34 catalysts for NH3-SCR

The high-temperature hydrothermal (HTH) stability is always a key factor that affects the NH3-SCR performance and limits the industrial applications of Cu/SAPO-34. Herein, two Cu/SAPO-34 catalysts with different grain sizes are HTH aged to investigate the role of the grain size of Cu/SAPO-34 in holding the structure stability of catalysts and the relationships between the grain size and deNOx performance over Cu/SAPO-34 during the HTH treatment. Characterization results illustrates that the relationship between the grain size and the stability of SAPO framework and the content of isolated Cu2+ ions. During the HTH treatment, CuO species more easily transfer to isolated Cu2+ species via migrating into the framework from the external surface of SAPO-34 for the larger-sized catalyst rather than the smaller-sized one. The re-distribution of Cu2+ in the larger-sized catalyst prevents Si-O(H)-Al from H2O attacking during HTH treatment. Therefore, the larger-sized Cu/SAPO-34 maintains stronger structural stability and higher deNOx activity than smaller-sized one after HTH treatment. This work provides a new strategy for design of high-temperature hydrothermal stabilized Cu/SAPO-34 for eliminating NOx emitted from diesel engines.

High-Value-Added Compound Recovery with High-Temperature Hydrothermal Treatment and Steam Explosion, and Subsequent Biomethanization of Residual Strawberry Extrudate.

This study was on the comparison of hydrothermal treatments at 170 °C (steam injection) and 220 °C (steam explosion) to solubilize the organic matter contained in residual strawberry extrudate, focusing on phenolic compounds that were susceptible to be extracted and on sugars. After the extraction step, the remaining strawberry extrudate phases were subjected to anaerobic digestion to generate biogas that would compensate the energy requirements of the suggested hydrothermal treatments and to stabilize the remaining waste. Hydrothermal treatment at 220 °C allowed the recovery of 2053 mg of gallic acid eq. per kg of residual strawberry extrudate. By contrast, after hydrothermal treatment at 170 °C, only 394 mg of gallic acid eq. per kg of residual strawberry extrudate was recovered. Anaerobic digestion processes were applied to the de-phenolized liquid phase and the solid phase together, which generated similar methane productions, i.e., around 430 mL CH4/g volatile solids, after both 170 °C and 220 °C hydrothermal treatments. Considering the latest observation, hydrothermal treatment at 220 °C is a preferable option for the valorization of residual strawberry extrudate (RSE) due to the high solubilization of valuable phenolic compounds that can be recovered.

Optimization of Hybrid Crystal with SAPO-5/34 on Hydrothermal Stability for deNOx Reaction by NH3

In order to deal with the challenge of the hydrothermal deactivation of selective catalytic reduction of NOx by NH3(NH3-SCR) catalyst and extend its lifetime, a novel Cu/SAPO-5/34 catalyst was prepared, and it almost maintains its deNOx performance with a high conversion rate of 90% NOx between 175 °C and 400 °C after undergoing the rigorous treatment at 800 °C for 12 h. Thus, Cu/SAPO-5/34 is more recalcitrant to the high-temperature hydrothermal deactivation than Cu/SAPO-34. Besides, the formation of N2O is always below 3×10−6(3 ppm) during the whole reaction temperature, performing an advanced catalytic selectivity. The effect of high-temperature hydrothermal treatment on the morphology, structure and texture property, the acid sites, as well as the active copper species were investigated. These characterizations manifest that the optimized high-temperature hydrothermal stability is associated closely with the good structural stability over Cu/SAPO-5/34-HT, which facilitates to preserve reaction sites, and then showing the better hydrothermal stability than Cu/SAPO-34.

Prepared hydrophobic Y zeolite for adsorbing toluene in humid environment

Abstract Decontamination of air or other gas streams loaded with low-concentration volatile organic compounds (VOCs) and high humidity is a prevalent task for adsorption using zeolites. Hydrophobic adsorbents were prepared with NaY zeolites as raw materials by the high-temperature hydrothermal treatment, and the degree of ion-exchange was considered as a key factor. Adsorbents were characterized by XRD, FTIR spectra, N2 adsorption-desorption isotherm, SEM, water contact angle, TG/DTG, and the adsorption capacities of water and toluene were evaluated by static adsorption test and dynamic adsorption breakthrough study. The results showed that high degree of ion-exchange was beneficial to dealumination from zeolite skeleton and crystal of zeolite remains intact in the high-temperature hydrothermal treatment. The framework silicon-aluminum ratio (SiO2/Al2O3) of modified zeolite obtained by high-temperature hydrothermal treatment reached 12.41 while the degree of ion-exchange was three (SY-3). Moreover, the hydrophobic index (HI) of SY-3 increased from 0.047 of initial NaY zeolite to 10.059. In addition, regeneration of SY-3 was easier than that of initial NaY zeolite. Our work also has further studied the mass transfer in the zeolite and mechanism of high-temperature hydrothermal treatment under the effect of different ion-exchange degree.

A reconstruction strategy for the synthesis of Cu-SAPO-34 with excellent NH3-SCR catalytic performance and hydrothermal stability

AbstractA reconstruction strategy has been developed to synthesize Cu-SAPO-34 with a wide crystallization phase region, high solid yield, and tunable Si and Cu contents. Cu-rich SAPO-34 was prepared from a Cu-amine complex, which acted as a precursor and Cu source for the reconstruction synthesis. The role of the Cu-amine complex as a template was restricted, which allowed easier control over the Cu and Si contents than in the previously reported “one-pot” synthesis method. Characterization of the material revealed that the Si(4Al) coordination environment dominates the synthesized Cu-SAPO-34 catalysts. High-temperature hydrothermal treatment increased the isolated Cu2+ content slightly, and the acid sites in the low-silica catalyst are more resistant to hydrothermal treatment than those of the existing catalysts. The obtained materials, especially the low-silica Cu-SAPO-34 sample, exhibit excellent catalytic activity and hydrothermal stability for the selective catalytic reduction of NOx by NH3 (NH3-SCR). In addition, the influence of the catalyst acidity on the NH3-SCR reaction was also investigated and is discussed. The high synthetic efficiency and outstanding catalytic performance make Cu-SAPO-34 synthesized by the reconstruction method a promising catalyst for the NH3-SCR process.

Effect of Ce Doping on Hydrothermal Stability of Cu-SAPO-18 in the Selective Catalytic Reduction of NO with NH3

The Ce-Cu-SAPO-18 samples were prepared by the ion exchange method. Physicochemical properties of the samples were systematically characterized by a number of analytical techniques, and Ce doping and hydrothermal temperature effects on NH3-SCR activity of Cu-SAPO-18 were also investigated. The results show that doping of Ce increased NH3-SCR activity and hydrothermal stability of the Cu-SAPO-18 sample. After Ce doping, a more amount of the isolated Cu2+ ions entered the D6R and the catalyst structure was more stable. The structure and catalytic activity of Ce-Cu-SAPO-18 remained almost intact after hydrothermal aging at 650 °C. After hydrothermal aging at 850 °C, however, the structure of Ce-Cu-SAPO-18 was greatly destroyed, and its catalytic activity declined remarkably. The high-temperature hydrothermal aging treatment led to decreases in amount of the isolated Cu2+ ions and acidic sites, destroying in the zeolitic structure, and drop in NH3-SCR activity.

Surface sulfonation and nitrification enhance the biological activity and osteogenesis of polyetheretherketone by forming an irregular nano-porous monolayer.

Polyether-ether-ketone (PEEK) is becoming a popular component of clinical spinal and orthopedic applications, but its practical use suffers from several limitations. In this study, irregular nano-porous monolayer with differently functional groups was formed on the surface of PEEK through sulfonation and nitrification. The surface characteristics were detected by field-emission scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectrometry, water contact angle measurements and Fourier transform infrared spectroscopy. In vitro cellular behaviors were evaluated by cell adhesion, morphological changes, proliferation, alkalinity, phosphatase activity, real-time RT-PCR and western blot analyses. In vivo osseointegration was examined through micro-CT and histological assessments. Our results reveal that the irregular nano-porous of PEEK affect the biological properties. High-temperature hydrothermal NP treatment induced early osteogenic differentiation and early osteogenesis. Modification by sulfonation and nitrification can broaden the use of PEEK in orthopedic and dental applications. This study provides a theoretical basis for the wider clinical application of PEEK. a To obtain a uniform porous structure, PEEK samples were treated by concentrated sulfuric acid and fuming nitric acid (82-80%) with magnetic stirring sequentially. b Effects of nanopores on biological behavior of bMSCS.

Effects of Cu/Al Mass Ratio and Hydrothermal Aging Temperature on Catalytic Performance of Cu/SAPO-18 for the NH3-SCR of NO in Simulated Diesel Exhaust

The Cu/SAPO-18 samples with different Cu/Al mass ratios were prepared, their catalytic activities for the NH3-SCR of NO in simulated diesel exhaust were evaluated, and effects of Cu/Al mass ratio and hydrothermal aging temperature on catalytic performance of Cu/SAPO-18 was examined. Physicochemical properties of the samples were characterized by means of various techniques. It is found that the activity of the sample changed with a rise in Cu/Al mass ratio, with the highest overall activity being achieved over the sample with a Cu/Al mass ratio of 0.045. The H2-TPR results indicate that the Cu/Al mass ratio could affect the distribution of Cu species, and the Cu/SAPO-18-0.045 sample possessed the highest amount of the isolated Cu2+ species. BET and XRD results reveal that the Cu/Al mass ratio exerted little effect on the structure of the sample. Low-temperature hydrothermal treatment had the least influence on the sample, and the effect of high-temperature hydrothermal treatment on the sample became increasingly obvious with a rise in hydrothermal treatment temperature. It is concluded that the hydrothermal aging treatment mainly affected the sample by destroying the structure, blocking the pores, migration and transformation of the Cu species, and changing the acidic sites of the sample.