Selective Production of Phenol on Bifunctional, Hierarchical ZSM-5 Zeolites.

Margarita Popova,Hristina Lazarova,Ágnes Szegedi,Magdolna R Mihályi,Pavletta Shestakova,Neli Koseva,Manuela Oykova

doi:10.3390/molecules26123576

Abstract

Mono- and bimetallic Ni-, Ru- and Pt-modified hierarchical ZSM-5 materials were prepared by impregnation technique and characterized by X-ray diffraction (XRD), N2 physisorption, temperature-programmed reduction (TPR–TGA), ATR–FTIR and solid state NMR spectroscopy. Formation of finely dispersed nickel, ruthenium and platinum species was observed on the bimetallic catalysts. It was found that the peculiarity of the used zeolite structure and the modification procedure determine the type of formed metal oxides and their dispersion and reducibility. The samples’ acidity was studied via FTIR spectroscopy of adsorbed pyridine. The changes in the zeolite structure were studied via solid-state NMR spectroscopy. The catalysts were investigated in a gas-phase hydrodeoxygenation, transalkylation and dealkylation reaction of model lignin derivative molecules for phenol production.

Highlights

Significant development in industrial activities has caused environmental hazards, irreparable damage to ecosystems and adverse consequences for human health [1,2,3]
Phenol is one of the most important aromatic chemicals used in industry with 8.9 million tons produced annually [12], which are mainly used as synthetic polymer precursors, pharmaceuticals and herbicides
The nickel content was predominantly exposed to the zeolite surface and could participate in the reaction12asofa1c7tive sites, whereas only a small part of the Pt2+ was accessible to the reactant molecules after its in situ reduction before the catalytic experiment

Summary

Introduction

Significant development in industrial activities has caused environmental hazards, irreparable damage to ecosystems and adverse consequences for human health [1,2,3]. The mono- and bi-component Pt-modified zeolites showed the presence of at least two different types of EFAl species represented by a narrow resonance at approximately 4 ppm and a broad signal centered at approximately 7 ppm. The mono- and bi-component Pt-modified zeolites showed the presence of at least two different types of EFAl species represented by a narrow resonance at approximately 4 ppm and a broad s8igonf 1a6l centered at approximately 7 ppm. The simultaneous modification by nickel and platinum led to higher activity and selectivity to phenol This effect could be explained by the stabilization of Al in tetrahedral position in 10Ni1Pt/Z-h as suggested by NMR in comparison to 1Pt/Z-h, and by the increase in the probably due to the higher degree of reduction in NiO in the presence of platinum, as this matches findings for other Pt/Ni catalysts [41,42]. The nickel content was predominantly exposed to the zeolite surface and could participate in the reaction12asofa1c7tive sites, whereas only a small part of the Pt2+ was accessible to the reactant molecules after its in situ reduction before the catalytic experiment

Synthesis of ZSM-5 Zeolite

Preparation of Hierarchical ZSM-5

Characterization

Catalytic Activity Measurements

Findings

Conclusions