Balanced distribution of Brønsted acidic sites and Lewis acidic sites for highly selective conversion of xylose into levulinic acid/ester over Zr-beta catalysts

2019 ◽  
Vol 21 (24) ◽  
pp. 6634-6645 ◽  
Author(s):  
Yuewen Shao ◽  
Kai Sun ◽  
Lijun Zhang ◽  
Qing Xu ◽  
Zhanming Zhang ◽  
...  
Keyword(s):  
Acid Ester ◽  
Levulinic Acid ◽  
Selective Conversion ◽  
Balanced Distribution ◽  
Lewis Acidic Sites ◽  
Acidic Sites

Highly selective conversion of xylose into levulinic acid/ester was achieved over the Zr-beta catalyst with balanced distribution of acidic sites.

Copper-based catalysts with tunable acidic and basic sites for the selective conversion of levulinic acid/ester to γ-valerolactone or 1,4-pentanediol

2019 ◽  
Vol 21 (16) ◽  
pp. 4499-4511 ◽  
Author(s):  
Yuewen Shao ◽  
Kai Sun ◽  
Qingyin Li ◽  
Qianhe Liu ◽  
Shu Zhang ◽  
...  
Keyword(s):  
Acid Ester ◽  
Levulinic Acid ◽  
Basic Sites ◽  
Selective Conversion

Selective conversion of levulinic acid/ester to γ-valerolactone or 1,4-pentanediol was achieved over copper-based catalysts with tunable acidic and basic sites.

Synergetic effects of hydrogenation and acidic sites in phosphorus-modified nickel catalysts for the selective conversion of furfural to cyclopentanone

2021 ◽  
Author(s):  
Guoming Gao ◽  
Yuewen Shao ◽  
Yong Gao ◽  
Tao Wei ◽  
Guanggang Gao ◽  
...  
Keyword(s):  
Nickel Catalysts ◽  
Acid Sites ◽  
Nickel Phosphide ◽  
Selective Conversion ◽  
Synergetic Effects ◽  
Balanced Distribution ◽  
Acidic Sites

Nickel phosphide species can tailor the selectivity of hydrogenation sites. The yields of CPO and CPL reached 93.5% over 15%Ni–25%P/Al2O3. The balanced distribution of hydrogenation/acid sites maximizes the yield of CPO.

Selective conversion of furfuryl alcohol to levulinic acid by SO3H-containing silica nanoflower in GVL/H2O system

2021 ◽  
Vol 171 ◽  
pp. 124-132
Author(s):  
Ruoqing Wang ◽  
Feng Shen ◽  
Yiwei Tang ◽  
Haixin Guo ◽  
Richard Lee Smith ◽  
...  
Keyword(s):  
Furfuryl Alcohol ◽  
Levulinic Acid ◽  
Selective Conversion

scholarly journals Effect of Fe Additives on the Catalytic Performance of Ion-Exchanged CsX Zeolites for Side-Chain Alkylation of Toluene with Methanol

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 829 ◽  
Author(s):  
Zhang ◽  
Yuan ◽  
Miao ◽  
Li ◽  
Shan ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Catalytic Performance ◽  
High Yield ◽  
Side Chain ◽  
Impregnation Method ◽  
Basic Sites ◽  
Lewis Acidic Sites ◽  
X Zeolite ◽  
Acidic Sites ◽  
Negative Effect

The side-chain alkylation of toluene with methanol was investigated over some Fe-modified Cs ion-exchanged X zeolite (CsX) catalysts prepared via the impregnation method using different iron sources. The absorption/activation behaviors of the reactants on the surface of the catalysts were studied by in situ Fourier-transform infrared (FT-IR) spectroscopy and temperature programmed desorption (TPD) mass measurements. Modification of CsX with a small amount of FeCl3 could result in a considerable decrease in catalytic activity, due mainly to the remarkable decrease in the density of acidic and basic sites of the catalysts. Interestingly, the Fe(NO3)3-modified CsX with an optimum Fe loading of 0.15 wt.% shows improved catalytic activity and high yield compared to the side-chain alkylation products. Modification of CsX with Fe(NO3)3 could also result in a decrease in basic sites of the catalyst. However, such a change does not bring an obvious negative effect on the adsorption/activation of toluene, while it could effectively inhibit the generation of the undesired bidentate formate. Furthermore, the introduced FeOx species (derived from the decomposition of Fe(NO3)3) may also act as new Lewis acidic sites to participate in the activation of methanol and to stabilize the formed active intermediates (i.e., unidentate formate). Therefore, modification of CsX with a suitable amount of Fe(NO3)3 may adjust its adsorption/activation ability for reagents by changing the acid–base properties of the catalyst, which can finally enhance the catalytic performance for the side-chain alkylation of toluene with methanol.

scholarly journals Low Temperature NH3-SCR over Mn-Ce Oxides Supported on MCM-41 from Diatomite

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3654 ◽  
Author(s):  
Mingxuan Ma ◽  
Xiaoyu Ma ◽  
Suping Cui ◽  
Tingting Liu ◽  
Yingliang Tian ◽  
...  
Keyword(s):  
Molecular Sieves ◽  
Synthesis Method ◽  
Molar Ratio ◽  
Impregnation Method ◽  
Catalyst Carrier ◽  
Nh3 Scr ◽  
Catalytic Material ◽  
Lewis Acidic Sites ◽  
Acidic Sites ◽  
Mcm 41

A series of MCM-41 molecular sieves with different molar ratio of template to silicon were synthesized through hydrothermal synthesis method by using cetyltrimethylammonium bromide (CTAB) as the template, diatomite as the silicon source. By using impregnation method, the Mn-Ce/MCM-41 SCR molecular sieve-based catalysts were prepared. The results observed that when the molar ratio of template to silicon was 0.2:1, the MCM-41 as catalyst carrier has the highest surface area and largest pore volume, it also presented typically ordered hexagonal arrays of uniform channels. The denitration catalytic material based on this carrier has a high number of Lewis acidic sites, and the denitration efficiency can reach more than 93%.

scholarly journals The ZSM-5-Catalyzed Oxidation of Benzene to Phenol with N2O: Effect of Lewis Acid Sites

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 44
Author(s):  
Cui Ouyang ◽  
Yingxia Li ◽  
Jianwei Li
Keyword(s):  
Active Sites ◽  
Acid Sites ◽  
X Ray Diffraction ◽  
Remarkable Feature ◽  
Chemisorbed Oxygen ◽  
Lewis Acidic Sites ◽  
Acidic Sites ◽  
Adsorption Desorption ◽  
Oxidation Of Benzene ◽  
N2o Selectivity

The oxidation of benzene to phenol (BTOP) with N2O as the oxidant has been studied with a variety of Fe/ZSM-5 catalysts. The literature has conclusively proven that Fe2+ sites are the active sites. However, some studies have suggested that the Lewis acidic sites (LAS) are responsible for the generation of the active chemisorbed oxygen. Nevertheless, there is no clear relationship between the LAS and the N2O selectivity to phenol. In an effort to elucidate the effects of LAS on BTOP with various ZSM-5 catalysts, we investigated the initial N2O selectivity to phenol. Here we show that the initial N2O selectivity to phenol is negative with the amount of LAS over a certain range. The catalyst H-ZSM-5-ST (H-ZSM-5 treated with water vapor) showed a remarkable initial N2O selectivity to phenol as high as 95.9% with a 0.021 mmol g−1 LAS concentration on the surface of the catalyst, while the Fe/ZSM-5 catalyst demonstrated the lowest initial N2O selectivity to phenol (11.7%) with the highest LAS concentration (0.137 mmol g−1). Another remarkable feature is that steaming was more effective than Fe ion exchange and high temperature calcining. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), N2-adsorption-desorption, UV-vis, NH3-TPD and pyridine Fourier transform infrared (FT-IR) techniques. Our results demonstrate how the concentration of LAS is likely to affect the initial N2O selectivity to phenol within a certain range (0.021–0.137 mmol g−1). This research has demonstrated the synergy between the active Fe2+ sites and LAS.

Exploring the Role of Hexanuclear Clusters as Lewis Acidic Sites in Isostructural Metal–Organic Frameworks

2019 ◽  
Vol 31 (11) ◽  
pp. 4166-4172 ◽  
Author(s):  
Jiafei Lyu ◽  
Xuan Zhang ◽  
Peng Li ◽  
Xingjie Wang ◽  
Cassandra T. Buru ◽  
...  
Keyword(s):  
Metal Organic Frameworks ◽  
Hexanuclear Clusters ◽  
Lewis Acidic Sites ◽  
Acidic Sites ◽  
Metal Organic
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