catalyst loading
Recently Published Documents


TOTAL DOCUMENTS

911
(FIVE YEARS 367)

H-INDEX

43
(FIVE YEARS 10)

2022 ◽  
Vol 23 (2) ◽  
pp. 799
Author(s):  
Svetlana A. Sorokina ◽  
Stepan P. Mikhailov ◽  
Nina V. Kuchkina ◽  
Alexey V. Bykov ◽  
Alexander L. Vasiliev ◽  
...  

Hydrogenation of levulinic acid (LA) obtained from cellulose biomass is a promising path for production of γ-valerolactone (GVL)—a component of biofuel. In this work, we developed Ru nanoparticle containing nanocomposites based on hyperbranched pyridylphenylene polymer, serving as multiligand and stabilizing matrix. The functionalization of the nanocomposite with sulfuric acid significantly enhances the activity of the catalyst in the selective hydrogenation of LA to GVL and allows the reaction to proceed under mild reaction conditions (100 °C, 2 MPa of H2) in water and low catalyst loading (0.016 mol.%) with a quantitative yield of GVL and selectivity up to 100%. The catalysts were successfully reused four times without a significant loss of activity. A comprehensive physicochemical characterization of the catalysts allowed us to assess structure-property relationships and to uncover an important role of the polymeric support in the efficient GVL synthesis.


Synthesis ◽  
2022 ◽  
Author(s):  
Zhi-Wei Ma ◽  
Chuan-Chuan Wang ◽  
Quan-Jian Lv ◽  
Xiao-Pei Chen ◽  
Ai-Qin Li ◽  
...  

AbstractA new tertiary amine-squaramide organocatalyst has been developed and applied to the asymmetric Michael addition of cyclic diketones to β,γ-unsaturated α-keto esters. The catalyst system performed well with a low catalyst loading of 1 mol% under mild reaction conditions. A series of synthetically and pharmaceutically useful chiral bicyclic compounds were obtained in high yields (up to 97%) with excellent enantioselectivities (up to 99 % ee). Furthermore, this catalytic system can be used efficiently in large-scale reactions with the yields and enantioselectivities being maintained.


2022 ◽  
Vol 12 (1) ◽  
pp. 76
Author(s):  
Muhammad Tanveer ◽  
Gokce Tezcanli ◽  
Muhammad Tahseen Sadiq ◽  
Syeda Memoona Kazmi ◽  
Nawal Noshad ◽  
...  

Diclofenac sodium (DCF) is a non-steroidal anti-inflammatory drug mainly used as an analgesic, arthritic and anti-rheumatic. This study deals with the degradation of diclofenac by photo catalytic-based advanced oxidation processes. Artificial UV lamp and solar rays have been applied to activate the ZnO catalyst, thereby generating highly oxidizing species. These species initiate the degradation process of the drug, which results in intermediates that finally dissociate into carbon dioxide and water. The solar reactor system is comprised of quartz and borosilicate tubes alternatively for the absorption and transmission of the solar rays to the pollutant sample. The degradation rate has been analyzed by composition analysis using high performance liquid chromatography. TOC and COD tests have also been conducted for degraded samples. ZnO catalyst loading was tested from 0.1 gm/L to 1 gm/L and the degradation rate showed a rising trend up to 0.250 gm/L, but further increase in loading resulted in a drop in degradation. Similarly, degradation is higher in acidic condition as compared to neutral or basic pH. The results showed a higher degradation rate for UV lamp irradiation as compared to the solar system. Moreover, TOC and COD reduction is also found to be higher for UV lamp photo catalysis.


Author(s):  
Chao Li ◽  
Duo-Duo Hu ◽  
Ruoxing Jin ◽  
Bing-Bing Wu ◽  
Cheng-Yu Wang ◽  
...  

A photoredox/nickel-catalyzed selective 1,4-arylsulfonation of 1,3-enynes to access structurally diverse sulfone-containing allenes has been established. This radical cascade transformation featured with easy manipulation, mild conditions, low catalyst loading, broad substrate...


Catalysts ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 45
Author(s):  
Ivy L. Librando ◽  
Abdallah G. Mahmoud ◽  
Sónia A. C. Carabineiro ◽  
M. Fátima C. Guedes da Silva ◽  
Francisco J. Maldonado-Hódar ◽  
...  

A supported gold nanoparticle-catalyzed strategy has been utilized to promote a click chemistry reaction for the synthesis of 1,2,3-triazoles via the azide-alkyne cycloaddition (AAC) reaction. While the advent of effective non-copper catalysts (i.e., Ru, Ag, Ir) has demonstrated the catalysis of the AAC reaction, additional robust catalytic systems complementary to the copper catalyzed AAC remain in high demand. Herein, Au nanoparticles supported on Al2O3, Fe2O3, TiO2 and ZnO, along with gold reference catalysts (gold on carbon and gold on titania supplied by the World Gold Council) were used as catalysts for the AAC reaction. The supported Au nanoparticles with metal loadings of 0.7–1.6% (w/w relative to support) were able to selectively obtain 1,4-disubstituted-1,2,3-triazoles in moderate yields up to 79% after 15 min, under microwave irradiation at 150 °C using a 0.5–1.0 mol% catalyst loading through a one-pot three-component (terminal alkyne, organohalide and sodium azide) procedure according to the “click” rules. Among the supported Au catalysts, Au/TiO2 gave the best results.


2021 ◽  
Vol 21 (2) ◽  
pp. 225
Author(s):  
Dessy Ariyanti ◽  
Filicia Wicaksana ◽  
Wei Gao

In this study, a polyvinylidene difluoride (PVDF) hollow fiber membrane module incorporated with TiO2 was submerged into a photocatalytic reactor to create a hybrid photocatalysis with membrane separation process (a submerged membrane photoreactor, SMPR), for advanced dyes wastewater treatment. The SMPR performance was assessed by the degradation of single component Rhodamine B (RhB) and degradation of mixed dyes (RhB and Methyl orange (MO)) in a binary solution. Several operational parameters such as the amount of catalyst loading, permeate flux, and the effect of aeration were studied. Fouling tendency on the membrane was also investigated to determine the optimum operating conditions. The results show that the synergetic effect of the low catalyst loading and permeate flux creates the environment for optimum light penetration for high photocatalytic activity as the hybrid system with low catalyst loading (0.5 g/L) and 66 L/m2h of flux with aeration at 1.3 L/min has proven to increase the photocatalysis performance by 20% with additional catalyst recovery. In addition, applying the low catalyst loading and flux permeate with aeration brings minimal fouling problems.


Author(s):  
Sadra Souzanchi ◽  
Laleh Nazari ◽  
Venkat Kasanneni ◽  
Zhongchao Tan ◽  
Charles Xu

Isomerization of glucose to fructose was studied over activated hydrotalcite as a catalyst in a continuous-flow tubular reactor. The synthetic hydrotalcite (HT), calcined hydrotalcite (HT-C) and activated hydrotalcite (calcined-rehydrated hydrotalcite (HT-C-R)) were characterized by TGA, XRD, BET surface area, and FT-IR analyses. The effects of operating conditions, including reaction temperature and retention time (in terms of both catalyst loading and feeding flow rate) on the isomerization reaction, were investigated. Glucose conversion and fructose selectivity were found to be more strongly dependent on retention time than reaction temperature. The fructose yield was mostly dependent on the feeding flow rate, and its maximum value of 18% corresponded to the lowest flow rate of 0.5 ml/min. The regenerated hydrotalcite catalyst showed that the catalyst activity could be restored through the calcination-rehydration process, and it showed good potential for recycling and reusability.


Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1542
Author(s):  
Mohamad Rasid Shera Farisya ◽  
Ramli Irmawati ◽  
Ishak Nor Shafizah ◽  
Yun Hin Taufiq-Yap ◽  
Ernee Noryana Muhamad ◽  
...  

In this research, a solid acid catalyst was synthesized to catalyse glycerol acetylation into acetins. The sulphated-titania catalysts were prepared via the wet impregnation method at different sulfuric acid concentrations (5%, 10%, 15%, and 20%) and denoted as 5SA, 10SA, 15SA, and 20SA, respectively. The synthesized catalysts were characterized using FTIR, XRD, TGA, BET, NH3-TPD, XRF, and SEM-EDX. The synthesized catalysts were tested on glycerol acetylation reaction at conditions: 0.5 g catalyst loading, 100–120 °C temperature, 1:6 glycerol/acetic acid molar ratios, and 2–4 h reaction time. The final product obtained was analysed using GC-FID. An increment in sulfuric acid concentration reduces the surface area, pore volume, and particles size. However, the increment has increased the number of active sites (Lewis acid) and strong acid strength. 15SA catalyst exhibited excellent glycerol conversion (>90%) and the highest selectivity of triacetin (42%). Besides sufficient surface area (1.9 m2 g−1) and good porosity structure, the great performance of the 15SA catalyst was attributed to its high acid site density (342.6 µmol g−1) and the high active site of metal oxide (95%).


Sign in / Sign up

Export Citation Format

Share Document