FUEL
·
2019
·
IF 5.128
Lina Han,Weiguo Ren,Bing Wang,Xingxing He,Lingjun Ma,Qihuang Huo,Jiancheng Wang,Weiren Bao,Liping Chang
In this work, a novel method is introduced to activate coal gangue (CG) for extraction of Si and Al species. The activation experiments were carried out using a stainless steel tube reactor (17 mL) and an autoclave reactor (1000 mL). Firstly, CG was activated by supercritical water added with alkali. It was found that the kaolinite phase of raw CG could be transformed into cancrinite, sodalite and kalsilite by using NaOH, Na 2 CO 3 and KOH as activators, respectively. Secondly, silica (SiO 2 ) and alumina (Al 2 O 3 ) were prepared by acid and alkali combination method. The extraction rates of Al 3+ and Si 4+ from the activated CG using KOH as activator were as high as 78.9% and 69.2%, respectively. The purity of SiO 2 and Al 2 O 3 products were 96.2% and 99.3%, respectively. The as-synthesized SiO 2 both from 17 mL and 1000 mL reactor exhibited very high specific surface areas of 710.0 m 2 ·g −1 and 872.8 m 2 ·g −1 , respectively. In addition, the SiO 2 after hydrophobic modification displayed excellent absorption selectivity for xylene.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Processes
·
2023
·Vol. 11
·期 6
·1779
·
IF 3.5
Qiao Zhu,Zhe Li,Yafei Song,Yujun Tong,Tao Yang,Zhenmin Cheng
The reduced solubility of inorganic salts in supercritical water has a significant impact on the stable operation of desalination facilities as it may lead to surface fouling due to salt deposition. In this study, the solubility of Na2SO4was experimentally determined to be 0.04–15.34 mmol/kg water at 23–25 MPa and 390–420 °C. To investigate the precipitation behavior of Na2SO4in supercritical water, a reactor with a heating bar was designed and the deposition effect of salt on the superheated surface in an autoclave was tested at a temperature of 390 °C and a pressure of 23 MPa. Then, the deposition mechanism of salt in the autoclave was analyzed and the temperature field in the reactor was simulated using CFD commercial software. The experimental results showed that Na2SO4was present on both the heating rod and the bottom of the autoclave with a loose salt layer. The simulation results indicated that the temperature near the heating rod was significantly higher than the bulk fluid temperature and it provided the temperature condition where the inorganic salt preferentially nucleated and precipitated. Nickel foam was chosen as the porous media carrier to investigate the selective precipitation of salt on different superheated surfaces. The results showed that nickel foam could collect a large amount of salt on the heating rod and change the state of the compact salt layer on the kettle bottom wall, providing a technical choice for salt recovery under supercritical conditions.Keywords:supercritical water;desalination;temperature effect;surface fouling
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMOSPHERE
·
2023
·
IF 8.8
Chenyu Wang,Xiaolong Ling,Chaoyue Wu,Chao He,Biao Gui,Weibo Sun
Phosphorus is a very important resource, and dewatered cyanobacteria contains a large amount of it. Basic additives, such as KOH, are often used to promote hydrogen production during supercritical water gasification (SCWG) of biomass, but their effects phosphorus transformation have rarely been investigated. In this study, SCWG of dewatered cyanobacteria with potassium salt and KOH was conducted in autoclave at 400 °C for 10 min, to investigate the effect of K + on the transformation of phosphorus under neutral and alkaline conditions. Results showed that K + increased the proportion of phosphorus in the solid phase from 88.4% to 90.8–98.3%. Furthermore, K + could promote the transformation of iron-combined phosphorus to calcium-combined phosphorus and occluded phosphate. Only when the reaction environment was alkaline, the proportion of phosphorus in the solid phase was significantly reduced to a minimum of 26.1%. When the amount of OH − was sufficient, can this part of phosphorus and organic phosphorus , which was decomposed and transformed by the promotion of OH − , be transferred to the liquid products. Results from this study laid a foundation simultaneously for hydrogen production and phosphorus recovery more environmentally and high-effectively.
研究领域:
环境科学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2017
·
IF 2.986
Yina Du,Ji-Xuan Liu,Yifeng Gu,Xin-Gang Wang,Fangfang Xu,Guo-Jun Zhang
Textured and untextured M n+1 AX n compounds, Ti 2 AlC and Ti 3 AlC 2 , namely MAX phases have been synthesized and examined with respect to their corrosion resistance in static supercritical water at 500 °C. The textured ceramics were obtained by hot forging process at high temperatures. Both X-ray diffraction and SEM analysis revealed well alignment of c -plane of MAX phases parallel to the hot-forging surface. Better corrosion resistance on the surface perpendicular to the hot-forged direction was verified by SEM. On the other hand, the side surfaces of the samples showed thick oxidation layers and abundant cracks. The (00 l ) faces consist of strongly bonded Ti 3 C 2 and Ti 2 C layers in Ti 3 AlC 2 and Ti 2 AlC, respectively, hence exhibit higher resistance to water corrosion. On the contrary, the side surfaces where most of weakly bonded interlayers of these hexagonal phases were exposed tend to be easily corroded especially through Al-layers. The corrosion process involved a phase transition of oxidized product, i.e. TiO 2 from anatase to rutile phase, which gave rise to the formation of cracks due to accompanied volume changes.
研究领域:
材料科学
·
腐蚀工程
✓ 已验证
产品关联
DOI
高影响因子
Water
·
2024
·Vol. 16
·期 22
·3235
·
IF 3
Qiao Xu,Fenfen Yan,Yujie Fan,Miao Gong
This work evaluated the alterations in the levels and types of polycyclic aromatic hydrocarbons (PAHs) within both liquid and solid products throughout the process of the catalytic supercritical water gasification of dewatered sewage sludge to examine the catalytic effect of various catalysts and the inhibit reaction pathways. The addition of Ni, NaOH, Na2CO3, H2O2, and KMnO4reduced the concentrations of PAHs, with Ni and H2O2showing the best performance. The concentrations of PAHs, especially higher-molecular-weight compounds in the residues, decreased sharply as the H2O2amount increased. At a 10 wt% H2O2addition, the levels of PAHs in the liquid and solid products were reduced by 91% and 88%, respectively. High-ring PAHs were not detected in the residues as the H2O2amount increased to an 8 wt%. H2O2addition evidently inhibits PAH formation by promoting the ring-opening reactions of initial aromatic compounds in raw sludge and inhibiting the polymerization of open-chain intermediate products. The addition of NaOH + H2O2or Ni + H2O2as combined catalysts significantly lowered PAH concentrations while increasing the H2yield. The addition of 5 wt% Ni + H2O2reduced PAH concentrations in the liquid and solid residues by 70% and 44%, respectively, while the H2yield escalated from 0.13 mol/kg OM to 3.88 mol/kg OM. Possible mechanisms associated with the reaction pathways of these combined catalysts are proposed.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2018
·
IF 4.229
Bin Li,Baohua Zhang,Qingqing Guan,Shanshuai Chen,Ping Ning
An effective Ni/CeO 2 catalyst prepared by the polyol reduction method for degrading phenol into CH 4 , H 2 and CO 2 in supercritical water (SCW) was developed. About 80% carbon gasification efficiency can be achieved at 525 °C and 60 min with 5 wt% phenol, 0.098 kg/m 3 water density and 0.5 g Ni/CeO 2 /g phenol catalyst, forming CH 4 and H 2 as the main gaseous products. Comparison study indicated that the efficiency of present Ni/CeO 2 catalyst was about 20% higher than that of a commercial catalyst, i.e., Ni/SiO 2 Al 2 O 3 from Sigma-Aldrich with 65 wt%Ni, at a reaction conditions of 500 °C and 30 min. The characterization analyses of BET, TPR, XRD , XPS and TEM indicated that there was a NiCe alloy formed in Ni/CeO 2 , which could be important to enhance the activities of the carbon gasification efficiencies and gas yields. A kinetic modelings were conducted and the results showed that the lnA and the activation energy (Ea) of gasification were 7.1 ± 0.5 and 58.1 ± 3.2 kJ/mol for the gaseous product, and were 2.6 ± 0.9 and Ea is 36.6 ± 5.6 kJ/mol for the char formation , respectively. The present Ni-based-metal Ni/CeO 2 catalyst is cheaper and has a potential application for the gasification to convert phenol into gases fuels in SCW process.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Cleaner Production
·
2023
·
IF 11.1
Shi Liu,Wen Cao,Fanrui Meng,Mingming Du,Wenwen Wei,Yunan Chen,Hui Jin,Liejin Guo
Supercritical water gasification (SCWG) of biomass waste as a new clean waste conversion technology is increasingly valued worldwide attributable to the unique properties of supercritical water (water: T > 374 °C, P > 22.1 MPa). However, the fate of conventionally contaminated elements such as nitrogen in this process still warrants further research to control potential contamination. In this work, uric acid was used as the model compound of nitrogenous components in chicken manure to investigate the transformation mechanism of nitrogen during the SCWG process. The effects of different temperatures (550–650 °C) and residence times (2–30 min) on the gasification characteristic of uric acid and the behaviour of nitrogen were experimentally explored. The results indicated that the higher temperatures and longer residence time significantly facilitated the uric acid gasification and nitrogen transformation. The maximum nitrogen conversion efficiency was 84.83%, and the maximum yield of NH 3 , H 2 , and CO 2 reached 20.20 mol/kg, 23.78 mol/kg, and 20.10 mol/kg at 650 °C and 30 min, respectively. Subsequently, the reaction pathways of nitrogen in uric acid were proposed in detail according to the product analysis. Finally, a kinetic model was developed to describe the SCWG process, especially the reaction kinetic of nitrogenous products. The results revealed that the hydrolysis reactions of uric acid led to a rapid increase in NH 3 yield in the initial stage of the SCWG process. As the process continued, the increase in NH 3 was mainly due to the deamidation reaction of small-molecule nitrogenous intermediates. Notably, NO x , NO 2 − , and NO 3 − were not detected in products, validating the inhibitory effects of the reducing environment of supercritical water on the generation of nitrogen oxides.
研究领域:
环境科学
·
能源工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2020
·
IF 9.038
Junhao Lin,Qinxiong Liao,Yaping Hu,Rui Ma,Chongwei Cui,Shichang Sun,Xiangli Liu
The generation of sulfur-containing pollution products affects the quality of biofuels obtained from the supercritical water gasification (SCWG) of sludge . This study investigates the effects of the gasification temperature, moisture content, and reaction atmosphere on the evolution of sulfur-containing compounds. The results showed that temperature was the key parameter causing the migration of sulfur from sludge to biogas and liquid products. The sludge decomposition reaction was dominated by ionic reactions at 360 °C, while the decomposition of organic matter was converted to free radical reactions as the temperature increased from 380 °C to 440 °C. The mercaptan and thioether contents of the bio-oil decreased to 0.3% at 440 °C. Correspondingly, the concentration of H 2 S increased from 6.7 ppm to 38.0 ppm. The decomposition of organic sulfur with an unstable structure (S-H bond and S-C bond) was the main cause of the increase in the content of H 2 S. Additionally, the solubility and oxidation properties of supercritical water were extremely strong. Some sulfur-containing organic compounds were converted into SO 4 2- via hydrolysis and oxidation reactions, forming sulfate crystals with heavy metals in the bio-char, which aided in achieving the synergistic immobilization of sulfur and heavy metals.
研究领域:
环境科学
·
能源工程
✓ 已验证
DOI
PubMed
高影响因子
FUEL
·
2021
·
IF 6.609
Ya-Qi Shan,Lin-Xin Yin,Oraléou Sangué Djandja,Zhi-Cong Wang,Pei-Gao Duan
Ru supported on activated carbon (C), Al 2 O 3 , CeO 2 , MgO, TiO 2 , and ZrO 2 were prepared and employed to boost supercritical water gasification (SCWG) of microalgae hydrothermal liquefaction (HTL) downstream water at 600 °C for 1 h. Effects of catalysts, water density, and Ru/C loading on total organic carbon (TOC) reduction, carbon gasification efficiency (CGE), and gas yield were examined. All the Ru catalysts showed a positive effect on TOC reduction and converted organics in the HTL downstream water to fuel gas, with H 2 and CH 4 as the two most abundant component. With the addition of Ru/C, almost complete removal of TOC, the highest CGE, and H 2 yield were achieved due to its largest metal dispersion. With the addition of Ru/C, increasing water density and catalyst loading favored TOC reduction and CGE increase as well as the total gas yield. The highest H 2 content of 50% and yield of 2.62 mmol/g (aq.) were obtained at the highest catalyst loading of 12.0 mg (Ru/C) /mL (aq.) . This study suggested that SCWG with the addition of Ru/C was a promising strategy to produce fuel gas rich in H 2 , from the organics in the microalgae HTL downstream water.
研究领域:
环境科学
·
能源工程
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2019
·
IF 4.084
Mi Yan,Hongcai Su,Dwi Hantoko,Ekkachai Kanchanatip,Fauziah Binti Shahul Hamid,Sicheng Zhang,Guobin Wang,Zhang Xu
In this study, the model food waste was gasified to hydrogen-rich syngas in a batch reactor under supercritical water condition. The model food consisted of rice, chicken, cabbage, and cooking oil. The effects of the main operating parameters including temperature (420–500 °C), residence time (20–60 min) and feedstock concentration (2–10 wt%) were investigated. Under the optimal condition at 500 °C, 2 wt% feedstock and 60 min residence time, the highest H 2 yield of 13.34 mol/kg and total gas yield of 28.27 mol/kg were obtained from non-catalytic experiments. In addition, four commercial catalysts namely FeCl 3 , K 2 CO 3 , activated carbon, and KOH were employed to investigate the catalytic effect of additives at the optimal condition. The results showed that the highest hydrogen yield of 20.37 mol/kg with H 2 selectivity of 113.19%, and the total gas yield of 38.36 mol/kg were achieved with 5 wt% KOH addition Moreover, the low heating value of gas products from catalytic experiments with KOH increased by 32.21% compared to the non-catalytic experiment. The catalytic performance of the catalysts can be ranked in descending order as KOH > activated carbon > FeCl 3 > K 2 CO 3 . The supercritical water gasification (SCWG) with KOH addition can be a potential applied technology for food waste treatment with production of hydrogen-rich gases.
研究领域:
能源转化
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2021
·
IF 5.816
Zhen Li,Miao Gong,Mengqi Wang,Aixin Feng,Linlu Wang,Peiyong Ma,Shoujun Yuan
Hydrogen has attracted significant attention as a clean energy source. Supercritical water gasification (SCWG) technology can produce hydrogen-rich gas while also disposing of sludge. The hydrogen yield from the SCWG of sludge is greatly increased when catalyzed by AlCl 3 . In this paper, a combined catalyst based on AlCl 3 was proposed to further increase the hydrogen yield of SCWG of dewatered sewage sludge (DSS). Analysis of the products from catalytic gasified of DSS and its model compounds were used to propose a catalytic mechanism and reaction pathway of the catalytic SCWG of DSS. Among the combined catalysts used for the SCWG of DSS, 10 wt% AlCl 3 –H 2 O 2 (mass ratio 8:2) had the best hydrogen production effect, and the hydrogen yield reached 8.88 mol/kg organic matter. This was 14% higher than when catalyzed by 10 wt% AlCl 3 . During catalysis with AlCl 3 , Al 3+ reacted with OH − in water and precipitated as Al(OH) 3 , which produced an acidic environment in the liquid product. Al(OH) 3 dehydrated to form an AlO(OH) and deposited in the solid product. A small amount of H 2 O 2 promoted the steam reforming reaction of organic matter in DSS, which increased the hydrogen yield. H 2 O 2 further promoted the hydrogen yield in an acidic environment. The catalytic effect of AlCl 3 was unaffected by H 2 O 2 . The H + generated by AlCl 3 during catalysis promoted H 2 O 2 to further depolymerized organic matter (such as humic substances) in DSS, so that AlCl 3 –H 2 O 2 catalyzed the SCWG of DSS to further increase the hydrogen yield. The order of hydrogen yield catalyzed by AlCl 3 –H 2 O 2 was guaiacol > humic acid > glycerol > alanine > glucose. Compared with AlCl 3 , AlCl 3 –H 2 O 2 reduced the hydrogen yield of glucose by nearly 20% and increased the hydrogen yield of humic acid by about 17% (25.81 mol/kg feed).
研究领域:
环境科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
WATER RESEARCH
·
2024
·
IF 11.4
Peng Feng,Donghai Xu,Youwei Zhi,Bing He,Shuzhong Wang,Yaling He,Yang Guo
This work aims to explore the ability of molten salt to solve salt deposition in supercritical water (SCW) related technologies including supercritical water oxidation and supercritical water gasification, with KNO 3 and Na 2 SO 4 as examples. In the pure KNO 3 solution, the two-phase layering of high-density KNO 3 molten salt (settling at the reactor bottom) and low-density saturated KNO 3 -SCW salt solution (flowing out at the top outlet of the reactor) was formed in a kettle-reactor with about 6.5 ratio of depth to inner diameter, thereby improving the accuracy of measured solubilities. The precipitation macro-characteristics of mixed KNO 3 and Na 2 SO 4 in SCW were investigated under different feed concentration conditions. The results showed that Na 2 SO 4 deposition on the reactor sidewall could be reduced by more than 90 % when the mass ratio of KNO 3 to Na 2 SO 4 in the feed was only 0.167. No visible salt deposition was observed on the sidewall when the ratio was 0.374. All solid deposited salts were converted into the liquid molten salt as the ratio reached 3.341, and thus could easily flow out of the reactor, without plugging. ‘Molten salt dissolution’ mechanism may provide a more plausible explanation for mixed KNO 3 and Na 2 SO 4 in SCW. In addition, the precipitation micro-mechanisms of mixed KNO 3 and Na 2 SO 4 , and the critical conditions of avoiding sidewall deposition and reactor plugging were proposed. This work is valuable for overcoming the salt deposition problem in SCW-related technologies.
研究领域:
化学工程
·
环境科学
·
超临界流体技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）