Ni‐W Catalysts Supported on HZSM‐5/HMS for the Hydrogenation Reaction of Aromatic Compounds: Effect of Ni/W Ratio on Activity, Stability, and Kinetics

Abstract

Ni‐W/HZSM5‐HMS catalysts were evaluated for the benzene hydrogenation reaction at 130–190°C. To study the catalyst characterization, X‐ray diffraction, X‐ray fluorescence, Fourier transform infrared, UV–vis, diffuse reflectance spectra, temperature‐programmed desorption of NH3, FT‐IR of adsorbed pyridine measurements (Py‐IR), H2 chemisorption, nitrogen adsorption–desorption, and TGA techniques were used. Kinetics of benzene hydrogenation was investigated under various hydrogen and benzene pressures, and the effect of reaction conditions on catalytic performance was studied. The results showed that bimetallic catalysts have better ability than a monometallic catalyst (Ni/HZSM5‐HMS) for this reaction, such as maximum benzene conversion (100%), minimum toluene conversion (1.76–40%), very low converted xylene, benzene selectivity (100%), good catalytic stability against coke deposition, and appropriate kinetic parameters.

Catalytic Performance and Kinetics Study over Novel Ni/Activated Carbon‐FSM‐16 Catalysts in the BTX Mixture for Benzene Selective Hydrogenation

“…The positive orders of hydrogen are in the range of 0.83–1.39 and good proximity with the reported literature values (0.30 to 2.33) . The benzene orders also are in the range of 0.65‐0.69 that are different from the results of similar works, which reported the amounts of −1 to 0.5 ,,…”

“…The presence of the peak at 645 nm represents the Ni +2 tetrahedral system and/or formation of the spinel structure ,, . Furthermore, the spectra of Ni‐containing composite catalysts do not return to baseline.…”

“…Selective hydrogenation of benzene as a volatile organic compound not only for providing a more efficient and cost‐effective route for the production of materials such as caprolactam and adipic acid, which are intermediates for nylons synthesis but also in order to eliminate the carcinogenic and environmental damaging effects is a substantial step in petrochemicals . Therefore, the design of high‐performance catalysts in this field has attracted the attention from many researchers ,…”

“…On the other hand, the use of the supports (alone or composite) is very common in order to prevent the metal nanoparticles sintering at high temperatures and increase the active phase dispersion to achieve more activity and stability . Many supports which have the different surface area and pore volume, including zeolites, metal oxides and carbon‐based materials, have been reported for this reaction.…”

“…Numerous kinetics models reported for hydrogenation of benzene are as follows: Langmuir‐Hinshelwood model that is the most important. In this model, the benzene molecules and hydrogen atoms are competitively adsorbed and reacted over the surface ,. The other proposed mechanisms are the sequential addition of hydrogen atoms and formation of cyclohexene (Horiuti‐Polanyi mechanism) and also the interaction of gaseous hydrogen molecules with benzene‐adsorbed molecules (Eley‐Rideal Mechanism) …”