scholarly journals In Situ Hydrodeoxygenation of Lignin-Derived Phenols With Synergistic Effect Between the Bimetal and Nb2O5 Support

2021 ◽  
Vol 9 ◽  
Author(s):  
Le Tong ◽  
Bo Cai ◽  
Ronghua Zhang ◽  
Junfeng Feng ◽  
Hui Pan
Keyword(s):  
Bimetallic Catalysts ◽  
Catalytic Properties ◽  
Acid Sites ◽  
Hydrogen Donor ◽  
Metal Particles ◽  
Impregnation Method ◽  
Reaction Pressure ◽  
Hydrogen Donors ◽  
Hydrogen Supply

Nb2O5-supported bimetallic catalysts were prepared by the impregnation method applied for the in situ hydrogenation of guaiacol. Guaiacol can be effectively transformed into cyclohexanol over different bimetallic catalysts using alcohol as the hydrogen donor. Meanwhile, the effects of different hydrogen donors such as isopropanol, sec-pentanol, and ethylene glycol on in situ hydrogenation of guaiacol were investigated in detail, and the results showed that isopropanol is the best hydrogen supply solvent. Then, the dependence of Ni–Mn/Nb2O5 properties on metal loading, reaction time, reaction temperature, and reaction pressure was studied for the in situ hydrogenation of guaiacol by using isopropanol as the hydrogen donor. Guaiacol can be completely converted, and the yield of cyclohexanol reached 71.8% over Ni–Mn/Nb2O5 with isopropanol as the hydrogen donor at 200°C for 5 h. The structures and characteristics of better catalytic properties of the Ni–Mn/Nb2O5 catalyst were determined by BET, NH3-TPD, XRD, XPS, SEM, and TEM, and the results indicated the particle size of the metal was small (approximately 10 nm) and the metal particles are finely dispersed in the whole support. Therefore, a large number of medium acid sites were generated on the 10Ni-10Mn/Nb2O5 with a large specific surface area, which could increase the interface between the metal and the support and may be beneficial to the hydrodeoxygenation of guaiacol.

scholarly journals Effect of Ce-modified Fe/ZSM-5 zeolite for selective catalytic reduction of NOx by ammonia

2020 ◽  
Vol 218 ◽  
pp. 03032
Author(s):  
Chenxi Li ◽  
Fanwei Meng ◽  
Qing Ye
Keyword(s):  
Selective Catalytic Reduction ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Impregnation Method ◽  
Adsorption Ability ◽  
In Situ Drifts ◽  
X Ray

A series of xCe-Fe/ZSM-5 (x = 0, 0.25, 0.5 wt%) samples were prepared by the impregnation method, and the catalytic activity was evaluated by the selective catalytic reduction of NOx with ammonia (NH3-SCR). The physicochemical properties of prepared samples were characterized by various techniques such as X-ray diffraction (XRD), Brunner-Emmet-Teller (BET) measurement, hydrogen temperatureprogrammed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), ammonia temperatureprogrammed desorption (NH3-TPD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). XRD and BET results demonstrated that Ce and Fe species were uniform dispersed on the surface of the ZSM-5 zeolite and the micropore structure of ZSM-5 was still maintained. H2-TPR analysis indicated that the doping of Ce created more isolated Ce4+ and Fe3+ on the surface of catalysts, and the abundant Ce4+ and Fe3+ could enhance the reduction ability of catalysts. XPS analysis suggested that the doping of Ce could generate more oxygen vacancies, thereby increasing the number of chemisorption oxygen. According to the in-situ DRIFTS and NH3-TPD results, Ce species provided more acidic sites, which is beneficial to the NH3 adsorption ability of ZSM-5 zeolite. Additionally, the abundant chemisorption oxygen, medium and strong Brønsted acid sites, excellent NH3 adsorption ability and outstanding reduction property are beneficial to the NH3-SCR reaction. Among all prepared samples, the 0.25Ce-Fe/ZSM-5 sample possessed the widest reaction temperature window and the best catalytic performance (NO conversion over 98% at 350-450 °C), which was associated with the abundant acid sites and remarkable adsorption ability of NH3, outstanding redox ability and abundant chemisorption oxygen after the doping of Ce.

scholarly journals Synthesis of Ni-Modified ZSM-5 Zeolites and Their Catalytic Performance in n-Octane Hydroconversion

2020 ◽  
Vol 8 ◽  
Author(s):  
Qiang Wei ◽  
Pengfei Zhang ◽  
Xiaodong Liu ◽  
Wenbin Huang ◽  
Xiayun Fan ◽  
...  
Keyword(s):  
Supported Catalysts ◽  
Synthesis Method ◽  
Textural Properties ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Impregnation Method ◽  
Isomerization Selectivity ◽  
Nimo Catalysts ◽  
Adsorption Desorption

Ni-modified ZSM-5 zeolites with different nickel contents were successfully prepared by the in situ synthesis method and the impregnation method. The synthesized samples were characterized by XRD, SEM, N2 adsorption–desorption isothermals, and Py-FTIR. The characterization results show that both the textural properties and crystallization of Ni-modified ZSM-5 zeolites were preserved well, and their acidic properties can be modulated after nickel modification. The corresponding NiMo catalysts supported on Ni-modified ZSM-5 zeolites were prepared by the incipient wetness co-impregnation method, and their catalytic performances were evaluated in n-octane hydroconversion. Compared to the those modified by the in situ synthesis method, ZSM-5 zeolite-supported catalysts modified by the impregnation method exhibit higher stability and higher isomerization selectivity. This is due to the synergistic effect between Brønsted acid sites and Lewis acid sites on the Ni-modified ZSM-5 zeolites, especially for the NiMo/1Ni-Z5 catalyst.

Nature and Catalytic Properties of In-Situ-Generated Brønsted Acid Sites on NaY

ACS Catalysis ◽  
2018 ◽  
Vol 9 (3) ◽  
pp. 1931-1942 ◽  
Author(s):  
Brian M. Murphy ◽  
Jingcheng Wu ◽  
Hong Je Cho ◽  
Juliana Soreo ◽  
Chenguang Wang ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brønsted Acid Sites ◽  
Brönsted Acid ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

scholarly journals In situ hydrogenation and decarboxylation of oleic acid into heptadecane over a Cu–Ni alloy catalyst using methanol as a hydrogen carrier

2018 ◽  
Vol 20 (1) ◽  
pp. 197-205 ◽  
Author(s):  
Zihao Zhang ◽  
Qiwei Yang ◽  
Hao Chen ◽  
Kequan Chen ◽  
Xiuyang Lu ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Bimetallic Catalysts ◽  
Hydrogen Donor ◽  
Ni Alloy ◽  
Hydrogen Carrier ◽  
Alloy Catalyst

In this work, supported Cu–Ni bimetallic catalysts were synthesized and evaluated for the in situ hydrogenation and decarboxylation of oleic acid using methanol as a hydrogen donor.

Transformation of right-running gasoline fraction and gaskondensate on bimetallic catalysts based on zeolit ZSM-5

2021 ◽  
pp. 12-17
Author(s):  
S.E. Mamedov ◽  
◽  
N.F. Akhmedova ◽  
D.S. Efimova ◽  
S.E. Mirzalieva ◽  
...  
Keyword(s):  
Bimetallic Catalysts ◽  
Bimetallic Catalyst ◽  
Catalytic Properties ◽  
Strong Acid ◽  
Acid Sites ◽  
Gasoline Fraction ◽  
Gas Condensate ◽  
Catalyst Composition ◽  
Liquid Products ◽  
Strong Acid Sites

Acidic and catalytic properties of bimetallic catalysts based on ZSM-5 zeolite modified with copper, cobalt and boron in the conversion of straight-run gasoline fraction of gas condensate were studied in a flow-through unit at atmospheric pressure, in the absence of hydrogen in the temperature range 350-4300C. It has been established that the introduction of modifiers (Cu, Co, B) into the zeolite leads to a sig-nificant decrease in the strength and concentration of acid sites. An increase in the copper concen-tration in the zeolite to 3.0 wt.% leads to a decrease in the concentration of strong acid sites from 542 to 332 mmol/g. The introduction of 2% Cu/HZSM-5 into the catalyst composition of the second modifier Co in an amount of up to 1.5 wt.% reduces the concentration of strong acid sites to 242 mmol/g. With the additional modification of the bimetallic catalyst 1.0% Co 2% Cu/HZSM-5 with boron in an amount of 0.5-1.5 wt.%, the concentration of strong acid sites further decreases to 112-198 mmol/g. On unmodified zeolite HZSM-5, which has strong acid sites, cracking and aromatization of hydro-carbons mainly take place. Isomerization of n-paraffin hydrocarbons that make up the gas conden-sate is not significant. As a result of the modification of HZSM-5 with copper in the amount of 1.0-3.0 wt. %.There is a significant increase in the catalyzate content of high-octane components: iso-paraffinic and aromatic hydrocarbons. Modification of the catalyst with 2% Cu/HZSM-5 Co in an amount of 0.5-1.0 wt.% increases its isomerizing activity, and additional modification with boron (0.5-1.5 wt.%) leads to an increase in the yield of liquid products. The relationship between the acid-ic and catalytic properties of modified catalysts has been established. The effect of increasing the isomerizing and aromatizing activity of the modified catalysts is associated with the nature, concen-tration of the modifier, and the ratio of weak and strong acid sites. The isomerizing and aromatizing activity of the catalyst is controlled by the nature and concentration of the modifier. The bimetallic catalyst 1.0% Co 2.0 Cu% 1.0% B/HZSМ-5 exhibits the highest activity in upgrading straight-run gasoline fraction of gas condensate, which makes it possible to obtain a gasoline component with an octane number of 86.5 according to IM at 3800C and a yield of 77.8 wt.%.

scholarly journals Promoting Effect of Ti Species in MnOx-FeOx/Silicalite-1 for the Low-Temperature NH3-SCR Reaction

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 566
Author(s):  
Jialiang Gu ◽  
Rudi Duan ◽  
Weibin Chen ◽  
Yan Chen ◽  
Lili Liu ◽  
...  
Keyword(s):  
Catalytic Reduction ◽  
Surface Acidity ◽  
Space Velocity ◽  
Acid Sites ◽  
Impregnation Method ◽  
Promoting Effect ◽  
Nh3 Scr ◽  
Nh3 Adsorption ◽  
Redox Ability

Manganese and iron oxides catalysts supported on silicalite-1 and titanium silicalite-1 (TS-1) are synthesized by the wet impregnation method for the selective catalytic reduction (SCR) of NOx with NH3 (NH3-SCR), respectively. The optimized catalyst demonstrates an increased NOx conversion efficiency of 20% below 150 °C, with a space velocity of 18,000 h−1, which can be attributed to the incorporation of Ti species. The presence of Ti species enhances surface acidity and redox ability of the catalyst without changing the structure of supporter. Moreover, further researches based on in situ NH3 adsorption reveal that Lewis acid sites linked to Mn4+ on the surface have a huge influence on the improvement of denitration efficiency of the catalyst at low temperatures.

Structure and composition of metal particles in Pt-Sn/Al2O3 bimetallic catalysts

1990 ◽  
Vol 48 (4) ◽  
pp. 278-279
Author(s):  
A. Sachdev ◽  
J. Schwank
Keyword(s):  
Bimetallic Catalysts ◽  
Bimetallic Catalyst ◽  
Size Structure ◽  
High Surface ◽  
High Surface Area ◽  
Metal Particles ◽  
Alloy Formation ◽  
Particle Size Range ◽  
Oxide Supports ◽  
Petroleum Fractions

Platinum - tin bimetallic catalysts have been primarily utilized in the chemical industry in the catalytic reforming of petroleum fractions. In this process the naphtha feedstock is converted to hydrocarbons with higher octane numbers and high anti-knock qualities. Most of these catalysts contain small metal particles or crystallites supported on high surface area insulating oxide supports. The determination of the structure and composition of these particles is crucial to the understanding of the catalytic behavior. In a bimetallic catalyst it is important to know how the two metals are distributed within the particle size range and in what way the addition of a second metal affects the size, structure and composition of the metal particles. An added complication in the Pt-Sn system is the possibility of alloy formation between the two elements for all atomic ratios.

Coherent electron nanodiffraction from clean silver nano particles in a UHV STEM

1993 ◽  
Vol 51 ◽  
pp. 1058-1059
Author(s):  
J. Liu ◽  
M. Pan ◽  
G. E. Spinnler
Keyword(s):  
Supported Catalysts ◽  
Imaging Techniques ◽  
Nano Particles ◽  
Metal Particles ◽  
Shape Structure ◽  
Dynamical Simulations ◽  
Small Metal Particles ◽  
Extract Information

Small metal particles have peculiar chemical and physical properties as compared to bulk materials. They are especially important in catalysis since metal particles are common constituents of supported catalysts. The structural characterization of small particles is of primary importance for the understanding of structure-catalytic activity relationships. The shape and size of metal particles larger than approximately 5 nm in diameter can be determined by several imaging techniques. It is difficult, however, to deduce the shape of smaller metal particles. Coherent electron nanodiffraction (CEND) patterns from nano particles contain information about the particle size, shape, structure and defects etc. As part of an on-going program of STEM characterization of supported catalysts we report some preliminary results of CEND study of Ag nano particles, deposited in situ in a UHV STEM instrument, and compare the experimental results with full dynamical simulations in order to extract information about the shape of Ag nano particles.

Influence of in-situ and ex-situ Cu-Fe doping in K-OMS-2 catalysts on dye degradation via Fenton-like reaction with focus on catalytic properties and performances

2021 ◽  
Vol 23 ◽  
pp. 101030
Author(s):  
Kitirote Wantala ◽  
Totsaporn Suwannaruang ◽  
Janthip Palalerd ◽  
Prae Chirawatkul ◽  
Narong Chanlek ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Dye Degradation ◽  
Ex Situ ◽  
Fe Doping

scholarly journals Insight into the Promoting Role of Er Modification on SO2 Resistance for NH3-SCR at Low Temperature over FeMn/TiO2 Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 618
Author(s):  
Huan Du ◽  
Zhitao Han ◽  
Xitian Wu ◽  
Chenglong Li ◽  
Yu Gao ◽  
...  
Keyword(s):  
Low Temperature ◽  
Catalyst Surface ◽  
Impregnation Method ◽  
In Situ Drifts ◽  
Tio2 Catalyst ◽  
Nh3 Scr ◽  
Nh3 Adsorption ◽  
So2 Resistance ◽  
Fast Scr

Er-modified FeMn/TiO2 catalysts were prepared through the wet impregnation method, and their NH3-SCR activities were tested. The results showed that Er modification could obviously promote SO2 resistance of FeMn/TiO2 catalysts at a low temperature. The promoting effect and mechanism were explored in detail using various techniques, such as BET, XRD, H2-TPR, XPS, TG, and in-situ DRIFTS. The characterization results indicated that Er modification on FeMn/TiO2 catalysts could increase the Mn4+ concentration and surface chemisorbed labile oxygen ratio, which was favorable for NO oxidation to NO2, further accelerating low-temperature SCR activity through the “fast SCR” reaction. As fast SCR reaction could accelerate the consumption of adsorbed NH3 species, it would benefit to restrain the competitive adsorption of SO2 and limit the reaction between adsorbed SO2 and NH3 species. XPS results indicated that ammonium sulfates and Mn sulfates formed were found on Er-modified FeMn/TiO2 catalyst surface seemed much less than those on FeMn/TiO2 catalyst surface, suggested that Er modification was helpful for reducing the generation or deposition of sulfate salts on the catalyst surface. According to in-situ DRIFTS the results of, the presence of SO2 in feeding gas imposed a stronger impact on the NO adsorption than NH3 adsorption on Lewis acid sites of Er-modified FeMn/TiO2 catalysts, gradually making NH3-SCR reaction to proceed in E–R mechanism rather than L–H mechanism. DRIFTS.

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