Abstract

Highly active metal chlorides grafted on silicoaluminophosphate number 5, MClx/SAPO-5 (M = Cu, Co, Sn, Fe and Zn) catalysts via simple grafting of respective metal chlorides (MClx) onto SAPO-5 are reported. The study shows that thermochemical treatment after grafting is essential to ensure the formation of chemical bondings between MClx and SAPO-5. In addition, the microscopy, XRD and nitrogen adsorption analyses reveal the homogeneous distribution of MClx species on the SAPO-5 surface. Furthermore, the elemental microanalysis confirms the formation of Si–O–M covalent bonds in ZnClx/SAPO-5, SnClx/SAPO-5 and FeClx/SAPO-5 whereas only dative bondings are formed in CoClx/SAPO-5 and CuClx/SAPO-5. The acidity of MClx/SAPO-5 is also affected by the type of metal chloride grafted. Thus, their catalytic behavior is evaluated in the acid-catalyzed acylation of 2-methylfuran under novel non-microwave instant heating conditions (90–110 °C, 0–20 min). ZnClx/SAPO-5, which has the largest amount of acidity (mainly Lewis acid sites), exhibits the best catalytic performance (94.5% conversion, 100% selective to 2-acetyl-5-methylfuran) among the MClx/SAPO-5 solids. Furthermore, the MClx/SAPO-5 solids, particularly SnClx/SAPO-5, FeClx/SAPO-5 and ZnClx/SAPO-5, also show more superior catalytic performance than common homogeneous acid catalysts (H2SO4, HNO3, CH3COOH, FeCl3, ZnCl2) with higher reactant conversion and catalyst reusability, thus offering a promising alternative for the replacement of hazardous homogeneous catalysts in Friedel–Crafts reactions.

Highlights

  • Furan and its acylated derivatives are important aromatic compounds that can be found in plants and microorganisms [1,2]

  • The solvent was removed via rotary evaporation before subjecting to thermochemical activation at 300 ◦ C to induce strong chemical bondings formation between the metal chlorides and the silicoaluminophosphate number 5 (SAPO-5) support

  • It can be concluded that strong chemical bonding between metal chloride and SAPO-5 had been formed after thermochemical activation

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Summary

Introduction

Furan and its acylated derivatives are important aromatic compounds that can be found in plants and microorganisms [1,2]. Zeolites and zeolite-like (AlPO-n, SAPO-n) solids are crystalline microporous materials composed of tetrahedral networks of TO4 (T = Si, Al and/or P) [13] These materials are very promising microporous solids from an environmental point of view, as catalysts, ion exchangers, molecular sieves and catalyst supports owing to their non-toxicity and high reusability [14,15,16,17]. Grafting of metal chlorides (e.g., GaCl3 , FeCl3 , AlCl3 ) on solid supports have found to be an effective approach to enhance the surface acidity of the solid catalysts [32,33,34,35,36]. The catalytic behavior of the grafted SAPO-5 solids is tested in the Friedel–Crafts acylation of 2-methylfuran under novel non-microwave instant heating conditions, and their catalytic performance and reusability are compared with the conventional acid catalysts

Experimental
Catalytic Testing
Characterization
Effect of Reaction Time and Temperature
Catalytic Comparative Study
Catalyst Reusability Test
Conclusions
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