Journal of Materials Chemistry A
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2021
·Vol. 9
·期 27
·15238-15245
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IF 12.732
Linying Wang,Dali Zhu,Juan Wang,Wenhao Cui,Jingfeng Han,Bing Li,Dong Fan,Peng Tian,Zhongmin Liu
An X-ray amorphous material with a CHA-like structure, named embryonic CHA zeolite, has been designed and employed for the synthesis of SSZ-13, which leads to ultra-fast crystallization (1.5–12 h), wide product SiO2/Al2O3 ratio (SAR = 22–100) and high yield (82.8–92.9%). The usage of N,N,N-trimethyl-1-adamantammonium hydroxide (TMAdaOH) for the synthesis can be controlled at unprecedentedly low amounts (TMAdaOH/SiO2 = 0.035–0.050). Characterization results reveal that the embryonic zeolite has a small particle size of 10–20 nm, large micro/mesopore volume and abundant double 6-ring units (subunits of the CHA structure). It provides ample active surface and subunits for the formation of the CHA structure and promotes the fast synthesis of SSZ-13 with a wide phase region. The resultant material (SAR = 23.2), after Cu2+ exchange, exhibits superior NH3-SCR activity and extraordinary hydrothermal stability (steaming at 800 °C for 16 h), implying its promising application for NOx removal. In addition, high-silica SSZ-13 shows good catalytic performance for the MTO reaction. It is anticipated that the embryonic zeolite-assisted strategy will benefit the synthesis of more industrially important zeolites.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Yang Gao,Xiaodong Wu,Rui Ran,Zhichun Si,Ziran Ma,Baodong Wang,Duan Weng
Monometallic (V/TiO 2 and Mo/TiO 2 ) and bimetallic (V-Mo/TiO 2 ) catalysts were prepared for selective catalytic reduction (SCR) of NO x with NH 3 at low temperatures (100–300 °C). The effect of MoO x on the dispersion of vanadia with different V 2 O 5 loadings was investigated on the basis of X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), N 2 adsorption–desorption, Raman spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), H 2 temperature-programmed reduction (H 2 -TPR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). As the molybdenum precursor, NH 4 Mo 7 O 24 increased the solution acidity and promoted polymerization of VO x in liquid phase. At a low vanadia loading, polymerization of VO x , the adsorption rate of NH 3 and transformation of active intermediate species NH 2 were enhanced by adding MoO x , while at a high vanadia loading, the steric hindrance became dominant leading to the formation of crystalline V 2 O 5 and MoO 3 and caused decline in SCR activity.
研究领域:
化学工程
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环境科学
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催化材料
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE ENERGY INSTITUTE
·
2022
·
IF 6.47
Pijun Gong,Feng He,Junlin Xie,Haitao Wu
Zn species that exist in the flue gas are dangerous toxicants for SCR catalysts, which will seriously damage its catalytic activity and service life. Hence, the multi-layered nanosheets γ-Al 2 O 3 with (110) facets were introduced into the CeTiOx catalyst to improve the Zn-poisoning resistance performance. Benefiting from the structural and compositional merits, as well as the superior reducibility, abundant acid sites, and chemisorbed oxygen, the 3%Zn–Ce 0.3 -Al 0.4 -Ti catalyst with multi-layered nanosheets structure exhibits excellent NH 3 -SCR activity, over 90% NO conversion between 240 °C and 340 °C. In addition, in situ DRIFTS results suggest the SCR reaction mainly follows L-H and E-R mechanisms on 3%-Ce 0.3 -Al 0.4 -Ti samples, result from the multi-layered nanosheets γ-Al 2 O structure improves the BET specific surface area and Ce 3+ , promotes the adsorption/activation of more NH 3 and NOx species. More interestingly, compared with CeO 2 and TiO 2 the Zn species prefer to absorbed on nanosheets γ-Al 2 O 3 with (110) facets, so it can effectively protect CeO 2 from poisoning as a sacrificial agent .
研究领域:
环境科学
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2019
·
IF 7.65
Guangpeng Yang,Xuesen Du,Jingyu Ran,Xiangmin Wang,Yanrong Chen,Li Zhang,Vladislav Rac,Vesna Rakic,John Crittenden
SCR activity of Cu-SAPO-34 catalyst was reduced by alkali metal ions. The alkali metals ions (Li + , Na + and K + ) have shown irregular influences on Cu-SAPO-34. The order of poisoning strengths under 400 °C was found to be: Na + > K + > Li + , which is not consistent with the basicities of their corresponding metals. Experimental results and calculations showed that the alkali metal ions readily replace H + and Cu 2+ /Cu + ions. These exchanges result in the loss of Brønsted acid sites and migration of isolated Cu 2+ ions in Cu-SAPO-34, which decrease the NH 3 -SCR activity. Both the basicity and ion diameter will affect the exchanging behavior of an alkali ion. Na + and Li + ions will influence both H + and Cu 2+ /Cu + ions but K + ions only preferably replace the H + . We hypothesize that K + cannot enter into a small ring (6-membered ring) to replace a Cu 2+ /Cu + ion because of its large ion diameter. The displaced Cu 2+ /Cu + ions will transfer to adjacent unbonded Al site to form a CuAlO 2 species.
研究领域:
环境科学
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催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 7
·3858-3868
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IF 2.936
Shuohan Yu,Sheng Xu,Bowen Sun,Yiyang Lu,Lulu Li,Weixin Zou,Peng Wang,Fei Gao,Changjin Tang,Lin Dong
Chromium oxide nano-particles with an average diameter of 3 nm covered by amorphous carbon (CrOx/C) were successfully synthesized. The synthesized CrOx/C materials were used for the selective catalytic reduction of NOx by NH3 (NH3-SCR), which shows superb NH3-SCR activity and in particular, satisfactory regeneration ability in the presence of SO2 compared with Mn-based catalysts. The as-prepared catalysts were characterized by XRD, HRTEM, Raman, FTIR, BET, TPD, TPR, XPS and in situ FTIR techniques. The results indicated presence of certain amounts of unstable lattice oxygen exposed on the surface of CrOx nano-particles with an average size of 3 nm in the CrOx/C samples, which led to NO being conveniently oxidized to NO2. The formed NO2 participated in NH3-SCR activity, reacting with catalysts via a “fast NH3-SCR” pathway, which enhanced th NH3-SCR performance of the CrOx/C catalysts. Furthermore, the stable lattice of the CrOx species made the catalyst immune to the sulfation process, which was inferred to be the cause of its superior regeneration ability in the presence of SO2. This study provides a simple way to synthesize stable CrOx nano-particles with active oxygen, and sheds light on designing NH3-SCR catalysts with highly efficient low temperature activity, SO2 tolerance, and regeneration ability.
研究领域:
催化
·
环境工程
·
材料科学
✓ 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）