Preparation of the Nb-P/SBA-15 catalyst and its performance in the dehydration of fructose to 5-hydroxymethylfurfural

Finely Tunable Carbon Nanofiber Catalysts for the Efficient Production of HMF in Biphasic MIBK/H2O Systems

This work proposes catalytic systems for fructose dehydration to 5-hydroxymethylfurfural using a series of functionalized carbon nanofibers. The catalysts were synthesized via finely selected covalent grafting in order to include a variety of functionalities like pure Bronsted acid, tandem Brønsted/Lewis acid, and tandem Lewis acid/Lewis base catalysts. After the characterization and evaluation of acidity strength and the amount of acid centers, the catalyst series was screened and related to the product distribution. The best-performing catalyst was also used to optimize the reaction parameters in order to achieve 5-hydroxymethylfurfural yields rounding at 60% without significant humin formation.

Unraveling Structural and Acidic Properties of Al-SBA-15-supported Metal Phosphates: Assessment for Glucose Dehydration

5-Hydroxymethylfurfural (5-HMF) synthesized through glucose conversion requires Lewis acid (L) site for isomerization and Brønsted acid (B) site for dehydration. The objective of this work is to investigate the influence of the metal type of Al-SBA-15-supported phosphates of Cr, Zr, Nb, Sr, and Sn on glucose conversion to 5-HMF in a NaCl-H2 O/n-butanol biphasic solvent system. The structural and acid property of all supported metal phosphate samples were fully verified by several spectroscopic methods. Among those catalysts, CrPO/Al-SBA-15 provided the best performance with the highest glucose conversion and 5-HMF yield, corresponding to the highest total acidity of 0.65 mmol/g and optimal L/B ratio of 1.88. For CrPO/Al-SBA-15, another critical parameter is the phosphate-to-chromium ratio. Moreover, DFT simulation of glucose conversion to 5-HMF on the surface of the optimized chromium phosphate structure reveals three steps of fructose dehydration on the Brønsted acid site. Finally, the optimum reaction condition, reusability, and leaching test of the best catalyst were determined. CrPO/Al-SBA-15 is a promising catalyst for glucose conversion to high-value-added chemicals in future biorefinery production.

Highly Selective Bio-hydrocarbon Production using Sidoarjo Mud Based-Catalysts in the Hydrocracking of Waste Palm Cooking Oil

In this work, Lapindo mud (LM) was used as catalyst support. This is because the Lapindo mud has a high SiO2 content of 45.33 %. This research aims to produce a hydrocracking catalyst based on Lapindo mud through impregnation of Ni and Pt metals as well as grafting amine groups. Ni and Pt metals impregnation using wet impregnation method followed by amine group grafting. The best catalyst in this study was NiPt-NH2/LM which contained Ni and Pt metals, surface area, and pore diameters of 1.68 wt.% and 0.4 wt.%, 6.59 m2/g, 15.51 nm, respectively. The effectiveness of the catalyst was tested against temperature and catalyst: feed ratio. The catalyst with the best activity and selectivity was tested for reusability 3 times through hydrocracking process. The yield of liquid products obtained in the hydrocracking process of WPO using NiPt-NH2/LM catalyst with the optimum temperature and the weight ratio of catalyst:feed at 550 oC was 79.4 wt. % which consists of hydrocarbon compound of 55.9 wt.%. The yield of liquid products obtained in the hydrocracking WPO using the used NiPt-BH2/LM catalyst was 28.4 wt.% which consists of hydrocarbon compound of 23.6 wt.%. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Glucose Conversion into 5-Hydroxymethylfurfural over Niobium Oxides Supported on Natural Rubber-Derived Carbon/Silica Nanocomposite

5-Hydroxymethylfurfural (HMF) is one of the most important lignocellulosic biomass-derived platform molecules for production of renewable fuel additives, liquid hydrocarbon fuels, and value-added chemicals. The present work developed niobium oxides (Nb2O5) supported on mesoporous carbon/silica nanocomposite (MCS), as novel solid base catalyst for synthesis of HMF via one-pot glucose conversion in a biphasic solvent. The MCS material was prepared via carbonization using natural rubber dispersed in hexagonal mesoporous silica (HMS) as a precursor. The Nb2O5 supported on MCS (Nb/MCS) catalyst with an niobium (Nb) loading amount of 10 wt.% (10-Nb/MCS) was characterized by high dispersion, and so tiny crystallites of Nb2O5, on the MCS surface, good textural properties, and the presence of Bronsted and Lewis acid sites with weak-to-medium strength. By varying the Nb loading amount, the crystallite size of Nb2O5 and molar ratio of Bronsted/Lewis acidity could be tuned. When compared to the pure silica HMS-supported Nb catalyst, the Nb/MCS material showed a superior glucose conversion and HMF yield. The highest HMF yield of 57.5% was achieved at 93.2% glucose conversion when using 10-Nb/MCS as catalyst (5 wt.% loading with respect to the mass of glucose) at 190 °C for 1 h. Furthermore, 10-Nb/MCS had excellent catalytic stability, being reused in the reaction for five consecutive cycles during which both the glucose conversion and HMF yield were insignificantly changed. Its superior performance was ascribed to the suitable ratio of Brønsted/Lewis acid sites, and the hydrophobic properties generated from the carbon moieties dispersed in the MCS nanocomposite.

Heparin Immobilized on Multiwalled Carbon Nanotubes for Catalytic Conversion of Fructose in Water with High Yield and Selectivity

Being a member of the glycosaminoglycan family of carbohydrates, native heparin is a highly sulfated polysaccharide. Herein, heparin was grafted onto polydopamine (PDA)- and poly(ethylene imine) (PEI)-coated multiwalled carbon nanotubes (MWCNTs) (heparin-PEI@PDA@MWCNT). The immobilized heparin consists of a sulfated repeating disaccharide unit, conferring a unique microenvironment when catalyzing fructose dehydration into 5-hydroxymethylfurfural (HMF). The hydrogen bonding interactions naturally occur between the disaccharide unit of heparin and the monosaccharide fructose, and the adjacent sulfonic acid groups catalyze the fructose dehydration. The reactions were performed in water, and heparin-PEI@PDA@MWCNT achieved an HMF yield of 46.2% and an HMF selectivity of 82.2%. For the dehydration of fructose in water, heparin-PEI@PDA@MWCNT exhibits advantages over published heterogeneous catalysts on the basis of HMF yield and HMF selectivity. Three aspects contribute to the environmentally benign processing: (1) the catalyst heparin is a natural sulfated polysaccharide; (2) the catalysis is carried out in water and not in organic solvents; and (3) fructose can be produced from a biomass resource.