燃料化学学报最新文献

{"title":"Preparation of Sm-doped Cu-Ce high sulphur-resistant CO oxidation catalysts by combustion co-precipitation method","authors":"Liang ZHANG ,&nbsp;Yajiao LI ,&nbsp;Na WANG ,&nbsp;Huidong XIE ,&nbsp;Kaiyue YANG ,&nbsp;Chang YANG ,&nbsp;Chengmin GE","doi":"10.1016/S1872-5813(25)60536-6","DOIUrl":"10.1016/S1872-5813(25)60536-6","url":null,"abstract":"<div><div>Cu-Ce catalysts have been extensively studied owing to their excellent low-temperature CO oxidation activity. However, they are prone to deactivation in the presence of both water vapor and sulfur. In this study, Ce-Cu-Sm CO oxidation catalysts with enhanced sulfur resistance were synthesized by Sm doping using three methods: combustion, co-precipitation, and acid solution synergistic co-precipitation. The mechanism underlying the improved sulfur resistance was investigated using XRD, TEM, N₂ adsorption and desorption, XPS, H₂-TPR, and CO-TPD techniques. The results revealed that, under the coexistence of 1% CO, 10% H₂O, and 0.01% SO₂, the 20Ce-5Cu-4Sm-CG catalyst (prepared via acid solution synergistic co-precipitation) maintained a 100% CO oxidation efficiency for 220 min at 220 °C and a space velocity of 60000 mL/(g·h). After 280 min, the performance of the 20Ce-5Cu-4Sm-CG catalyst decreased to 70%, which was 1.3 times and 2.5 times higher than that of the 20Ce-5Cu-4Sm-C and 20Ce-5Cu-C catalysts prepared by the co-precipitation method, respectively. Characterization analysis revealed that Sm doping increased the CeO₂ crystal size to a certain extent and reduced the specific surface area of the catalyst. However, it also enhanced the concentrations of Ce³⁺, Cu⁺, and surface oxygen atoms, as well as the ratio of O_α and the number of oxygen vacancies in the CeO₂ lattice, which collectively improved the ability of the catalyst to oxidize CO under sulfur-containing atmosphere. The acid solution combustion synergistic co-precipitation method not only enhanced these five key properties for CO oxidation mentioned above, but also facilitated the formation of coordination complexes with the acid solution and Sm ions during combustion. These complexes were incorporated into the CeO₂ lattice to form a homogeneous solid solution, which made the catalyst particle size more uniform and the specific surface area larger, and eliminated the adverse effects of Sm doping on the surface structure. As a result, the oxidation ability of the catalyst was further improved. In summary, the 20Ce-5Cu-4Sm catalyst, prepared via the acid solution combustion and co-precipitation method, exhibits excellent sulfur resistance and enhances the performance of non-precious metal oxide CO oxidation catalysts for applications in sulfur-containing environments.</div></div>","PeriodicalId":15956,"journal":{"name":"燃料化学学报","volume":"53 7","pages":"Pages 1081-1092"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrodesulfurization of dibenzothiophene over NiMoP/Al2O3 bimetallic phosphide catalyst","authors":"Liangliang ZHANG ,&nbsp;Jiaping LU ,&nbsp;Wanxi LI ,&nbsp;Boqiong LI ,&nbsp;Cailong XUE ,&nbsp;Hefei KANG ,&nbsp;Yajie LIU","doi":"10.1016/S1872-5813(24)60530-X","DOIUrl":"10.1016/S1872-5813(24)60530-X","url":null,"abstract":"<div><div>Preparation of highly active hydrodesulfurization catalysts is extremely meaningful for the sulfur removal from thiophene substances. In this work, commercial nano-Al₂O₃ with mesoporous structure supported monometallic phosphide (NiP/Al₂O₃ and MoP/Al₂O₃) and bimetallic phosphide (NiMoP/Al₂O₃ with various Ni/Mo molar ratio) catalysts are successfully prepared by temperature-programmed reduction. X-ray diffraction (XRD) result shows the Ni/Mo molar ratio affect the crystal phase in catalysts. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) characterizations co-confirm the interact between Ni and Mo elements in bimetallic phosphide. Catalyst evaluation in hydrodesulfurization of dibenzothiophene shows that bimetallic phosphide samples exhibit better catalytic performance than monometallic phosphide. 62.1% conversion and 86.3% biphenyl selectivity with 30 h stability are achieved over NiMoP/Al₂O₃ (Ni/Mo=1:1) catalyst at 400 °C under 3 MPa H₂. All characterization results demonstrate that the improved activity of bimetallic phosphide owes to the Ni-Mo synergistic effect in NiMoP/Al₂O₃ (Ni/Mo=1:1) catalyst. This finding provides a guide to the design of bimetallic catalyst with synergistic effect.</div></div>","PeriodicalId":15956,"journal":{"name":"燃料化学学报","volume":"53 7","pages":"Pages 1072-1080"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The reactivity of CO with different lattice oxygens on Cu doped CeO2(111): A DFT study","authors":"Yuan LI ,&nbsp;Yisong ZHENG ,&nbsp;Hao WANG ,&nbsp;Honghao WANG ,&nbsp;Caishun ZHANG ,&nbsp;Shaozheng HU ,&nbsp;Jiao HAN ,&nbsp;Lei ZHANG ,&nbsp;Zhixian GAO","doi":"10.1016/S1872-5813(24)60512-8","DOIUrl":"10.1016/S1872-5813(24)60512-8","url":null,"abstract":"<div><div>The adsorption of CO on different lattice oxygen sites in Cu doped CeO₂(111) was studied by DFT method, and the geometrical structure and electronic properties of adsorption systems were analyzed. The results showed that CO interacted with lattice oxygen on the first layer formed CO₂. However, when adsorbed on the second layer lattice oxygen, carbonate species were formed with the participation of first layer lattice oxygens, i.e., CO co-adsorbed on first and second layer lattice oxygens. For the second layer adsorption, the absolute CO adsorption energy was big on the Oss nearby Cu. This kind of carbonates was thermodynamically stable, and it was attributed to the facilitation of Cu on CO adsorption, manifested by an electron migration behavior from the C 2<em>p</em> orbitals to the Cu 3<em>d</em> orbitals. However, the absolute CO adsorption energy on the Oss away from Cu was small. Compared to the formation of carbonates, the formation CO₂ had very small absolute adsorption energy, suggesting the formed carbonates on second layer was stable. Further, when CO adsorbed on the systems with a carbonate, the absolute CO adsorption energy was significantly smaller than that of the non-carbonated system, indicating that the formation of carbonates inhibited CO oxidation on Cu/CeO₂(111). Therefore, the formation of carbonates was unfavorable for CO oxidation reaction on Cu/CeO₂(111). The results of this study provide theoretical support for the negative effect of CO₂ on ceria-based catalysts.</div></div>","PeriodicalId":15956,"journal":{"name":"燃料化学学报","volume":"53 6","pages":"Pages 906-917"},"PeriodicalIF":0.0,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144331443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research progress of catalysts for synthesis of glycerol carbonate form glycerol and urea","authors":"Yuhua WANG ,&nbsp;Hongguang LI ,&nbsp;Liang DING ,&nbsp;Yongli KOU ,&nbsp;Wenbo QI ,&nbsp;Ning ZHAO","doi":"10.1016/S1872-5813(25)60538-X","DOIUrl":"10.1016/S1872-5813(25)60538-X","url":null,"abstract":"<div><div>Transformation of urea and glycerol to glycerol carbonate is an environmental friendly and economical process. Catalysts play an indispensable role in the process. Although many catalysts have been developed, the performance of the catalysts still cannot meet the needs of industrialization. In this paper, research progress of the homogeneous and heterogeneous catalysts of the reaction over the past 20 years were reviewed systematically. According to the types and active centers of catalysts, the catalysts were classified systematically and analyzed in detail. The typical reaction mechanisms were also summarized. The research and development direction of catalysts is made more explicit through systematic classification and mechanism analysis. The article reveals more novel catalysts have been designed and used for the reaction, such as mixed metal oxides with special structures, solid wastes and non-metallic materials. This work summarized the current state of research and prospected possible routes for design of novel catalysts. It is hoped that this review can provide some references for developing efficient catalysts.</div></div>","PeriodicalId":15956,"journal":{"name":"燃料化学学报","volume":"53 6","pages":"Pages 964-982"},"PeriodicalIF":0.0,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144330786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of influencing factors on the properties of coal-to-direct liquefied diesel","authors":"Zhendong QI ,&nbsp;Linsheng LI ,&nbsp;Xingbao WANG ,&nbsp;Jie FENG ,&nbsp;Wenying LI","doi":"10.1016/S1872-5813(24)60517-7","DOIUrl":"10.1016/S1872-5813(24)60517-7","url":null,"abstract":"<div><div>To improve the quality of coal-to-direct liquefied diesel, with the help of machine learning method, the properties prediction model of coal-to-direct liquefied diesel was established, in which the chemical structure and diesel properties of each component of a coal-to-direct liquefied diesel were studied. The oil sample used was the finished diesel from a coal-to-direct liquefaction facility at Erdos in 2023 with an annual oil production of one million tons. Descriptive statistics and correlation analysis were conducted on the hydrocarbon composition of the oil sample and the properties of the diesel. It was found that the hydrocarbon composition was predominantly composed of paraffin and cycloparaffin, accounting for 96.57% of the total hydrocarbon composition, with the monocycloparaffin being the most abundant. The analysis of the diesel quality test results showed that the diesel met the commercial diesel quality specifications, with good combustion performance, low-temperature fluidity, and environmental performance. From Pearson correlation coefficient, it was found that some variables had a high degree of correlation. To avoid the impact of multicollinearity on the model interpretation, a tree model algorithm was chosen to establish the model. Random forest (RF) algorithm, light gradient boosting machine algorithm and extreme gradient boosting algorithm were individually used to establish the prediction model that can evaluate the physical characteristic properties of coal-to-direct liquefied diesel, such as density, kinematic viscosity and cetane number, respectively, and the fitting of each algorithm to the diesel combustion performance was compared and analyzed. The results show that the RF model has good fitting performance and high accuracy. On the training set, the determination coefficients (<em>R</em>²) of density, kinematic viscosity and cetane number were 0.946, 0.916 and 0.814, respectively, and the mean absolute percentage error were 0.073, 0.646 and 0.4, respectively. On the test set, the determination coefficients (<em>R</em>²) for density, kinematic viscosity, and cetane number were 0.976, 0.865, and 0.765, respectively, while the corresponding mean absolute percentage error were 0.48, 2.86, and 0.957, respectively. The analysis showed that the contents of paraffin, tricyclic alkane and alkyl benzene had significant effects on the density, kinematic viscosity and cetane number of coal-to-direct liquefied diesel, while the contents of naphthalene and tricyclic aromatic hydrocarbons had little effect on the above properties. Increasing paraffin content will reduce the density and kinematic viscosity of coal-direct liquefied diesel, but will help increase the cetane number of diesels. The increase in the tricyclic alkane content and the alkyl benzene content will increase the density and kinematic viscosity of coal-direct liquefied diesel, but will reduce the cetane number of diesels.</div></div>","PeriodicalId":15956,"journal":{"name":"燃料化学学报","volume":"53 6","pages":"Pages 827-835"},"PeriodicalIF":0.0,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144330909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine learning assisted study of the transition metal phosphides catalyst for the water electrolysis to produce hydrogen","authors":"Yuming LI ,&nbsp;Yanwen XU ,&nbsp;Huanhuan WANG ,&nbsp;Hairuo ZHU ,&nbsp;Lina MA ,&nbsp;Yajun WANG","doi":"10.1016/S1872-5813(24)60525-6","DOIUrl":"10.1016/S1872-5813(24)60525-6","url":null,"abstract":"<div><div>In recent years, hydrogen production by water electrolysis has become an important strategy of energy transformation in China, where the design of efficient catalysts for hydrogen evolution reaction (HER) is a key issue. In this regard, transition metal phosphides (TMPs) are considered important non-precious metal catalysts in water electrolysis owing to their low price and high hydrogen production efficiency. However, experimental screening of highly active TMPs catalysts is time-consuming and challenging. This study provides a simple and effective method for rapidly screening highly efficient HER electrocatalysts based on machine learning and big-data analysis. Four machine learning algorithms, namely support vector regression (SVR), K-nearest neighbour (KNN), random forest regression (RF) and extreme gradient boosting (XGBoost), were developed to predict the catalytic performance of various transition metal phosphides reported in the literature in HER. After evaluating the four algorithms by RMSE and <em>R</em>², it was found that the RF algorithm has excellent prediction ability for overpotential, while the XGBoost algorithm predicts better for the Tafel slope. It is concluded that the contents of Ni, Co and Fe have a significant influence on the catalytic performance and highly active catalysts may be prepared by fine adjustment of their contents in the future.</div></div>","PeriodicalId":15956,"journal":{"name":"燃料化学学报","volume":"53 6","pages":"Pages 1-11"},"PeriodicalIF":0.0,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144331007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Catalyzed oxidative desulfurization of coal tar pitch with trifluoroacetic acid/choline chloride eutectic solvent","authors":"Chenpeng ZHAO ,&nbsp;Rui ZHANG ,&nbsp;Chunfeng MU ,&nbsp;Dekang LI ,&nbsp;Dakui ZHANG ,&nbsp;Haifeng LIU ,&nbsp;Lijun JIN ,&nbsp;Ying HE ,&nbsp;Haoquan HU","doi":"10.1016/S1872-5813(24)60516-5","DOIUrl":"10.1016/S1872-5813(24)60516-5","url":null,"abstract":"<div><div>To avoid the adverse effects of sulfur in coal tar pitch (CTP) on properties of the prepared carbon materials and environment, organic acids with different acidity and choline chloride (ChCl) were selected to prepare deep eutectic solvents (DES) by low-temperature heating, and H₂O₂ as the oxidant to compose a catalytic oxidation-extraction desulfurization system of CTP. The effects of DES composition, oxidation temperature, oxidation time, and H₂O₂ dosage on desulfurization of CTP were investigated. The results show that trifluoroacetic acid (TFA)/ChCl DES has a certain effect in catalyzing the oxidative desulfurization of CTP, and the optimal desulfurization rate of CTP reaches 38.7%. The products obtained under various reaction conditions were analyzed by means of elemental analysis, FT-IR, XRD and XPS. The results show that the oxidative desulfurization of CTP catalyzed by acidic DES not only greatly improves hydrophilicity of CTP to solvent by introducing a certain amount of oxygen-containing functional groups, but also changes surface micromorphology of CTP, resulting in cracks and small particles. All these promote oxidation of thiophene sulfur in CTP to sulfone, which is further oxidized to soluble sulfate, thereby achieving sulfur removal. At the same time, oxygen content of CTP after DES catalytic oxidation treatment is relatively low, which has little effect on crystal alignment of carbonized pitch char. This work provides a technical basis for expanding high-value utilization of high-sulfur CTP.</div></div>","PeriodicalId":15956,"journal":{"name":"燃料化学学报","volume":"53 6","pages":"Pages 836-847"},"PeriodicalIF":0.0,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144331008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance of honeycomb ceramic alumina supported Fe-Cr composite catalyst in the flue gas DeNOx by selective catalytic reduction with CO","authors":"Dongke LI ,&nbsp;Yuxue SUN ,&nbsp;Yu HAN ,&nbsp;Xiaoxing FAN ,&nbsp;Qiang GUO","doi":"10.1016/S1872-5813(24)60522-0","DOIUrl":"10.1016/S1872-5813(24)60522-0","url":null,"abstract":"<div><div>Using CO for the selective catalytic reduction (CO-SCR) of NO_<em>x</em> can significantly reduce the De-NO_<em>x</em> cost of boiler flue gas treatment. In this work, the catalytic performance of honeycomb ceramic alumina supported Fe-Cr composite (Fe-Cr/HCA) in the flue gas DeNO_<em>x</em> by CO-SCR was investigated at high temperature and the catalyst preparation parameters like the bimetallic ratio, aging temperature and metal loading amount were optimized. The results indicate that a solid solution of FeCr₂O₄ is formed on the Fe-Cr/HCA catalyst surface and the synergy between Fe₂O₃ and Cr₂O₃ greatly promote the De-NO_<em>x</em> efficiency by CO-SCR. In particular, the Fe-Cr/HCA catalyst, prepared with a Fe/Cr ratio of 1, aging temperature of 300 °C and impregnation for 15 times, exhibits excellent performance in the CO-SCR of NO, where the NO conversion approaches 100% at 400–800 °C under the tested conditions. Additionally, the catalyst impregnated six times can be utilized in practical applications.</div></div>","PeriodicalId":15956,"journal":{"name":"燃料化学学报","volume":"53 6","pages":"Pages 927-934"},"PeriodicalIF":0.0,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144331444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Erratum regarding previously published articles","authors":"","doi":"10.1016/S1872-5813(25)00007-6","DOIUrl":"10.1016/S1872-5813(25)00007-6","url":null,"abstract":"","PeriodicalId":15956,"journal":{"name":"燃料化学学报","volume":"53 6","pages":"Pages 983-984"},"PeriodicalIF":0.0,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144330787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Production of ethanol from cellulose in aqueous phase with Pt-Ni@C catalysts","authors":"Xiao LU ,&nbsp;Zhouwen LI ,&nbsp;Li ZHAO ,&nbsp;Xuewei ZHANG ,&nbsp;Guangmai ZHAO ,&nbsp;Kaixin JIN ,&nbsp;Wanpeng LI ,&nbsp;Haiyong WANG ,&nbsp;Dalei ZHANG ,&nbsp;Chenguang WANG","doi":"10.1016/S1872-5813(24)60524-4","DOIUrl":"10.1016/S1872-5813(24)60524-4","url":null,"abstract":"<div><div>A series of Pt-Ni@C catalysts with different Pt/Ni@C mass ratios were prepared using deposition precipitation method. The effect of the loading amounts of Pt on the synthesis of ethanol by cellulose hydrogenation reduction was studied. The structure-performance relationship of the catalyst was clarified. The results showed that the Pt/Ni@C catalyst achieved the complete conversion of high concentration of cellulose under H₂ environment at 200 ℃, 5.5 MPa. When the concentration of cellulose reached 50 g/L, the ethanol concentration in the solution was 13.3 g/L with yield of 31%. The valence state of the Pt species, the ordering degree of carbon and the microstructure of the catalyst were characterized by means of XRD, XPS, Raman and TEM. The Ni atoms wrapped by the carbon layer of the catalyst showed an electron-rich state through electron migration with the surface carbon layer. The electron-negative surface of Pt-Ni@C effectively break the C–O and C–C bonds of the intermediates. Compared with traditional carbon-based catalysts, the amount of surface active sites increased by loading small amount of Pt. The Pt promoted the activation of hydrogen, and the synergistic of electron-rich surface and the trace phosphoric acid led to excellent activity of the Pt-Ni@C.</div></div>","PeriodicalId":15956,"journal":{"name":"燃料化学学报","volume":"53 6","pages":"Pages 863-871"},"PeriodicalIF":0.0,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144330910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}