Hydrolysis of dimethyl terephthalate to terephthalic acid on Nb‐modified HZSM‐5 zeolite catalysts

Abstract

BACKGROUND: Whether waste polyethylene terephthalate (PET) can be effectively recycled is one of the main challenges of the current environmental problems. The hydrolysis of dimethyl terephthalate (DMT) to terephthalic acid (TPA) over Nb-modified HZSM-5 zeolite was studied. Nb/HZSM-5 zeolites with different loadings were prepared and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, NH 3 -temperature programmed desorption and pyridine adsorption infrared spectroscopy. The effects of different reaction conditions on the conversion of DMT and TPA yield were investigated.RESULTS: The yield of TPA strongly depends on the reaction conditions and the loading of Nb. The niobium phase exists in the form of Nb 2 O 5 on the zeolite and interacts with the surface of HZSM-5 to produce the active site of Brønsted acid. The yield of TPA is closely related to the concentration of Brønsted acid sites. On 0.6Nb/HZSM-5 catalyst, the yield of TPA is highest, at about 94%.CONCLUSION: Nb/HZSM-5 catalyst has excellent catalytic activity and high stability for DMT hydrolysis. In addition, the product TPA prepared in this study can be directly applied to the current PET production supply chain, providing a promising catalytic route.

One-Step Synthesized Solid Acid Catalyst with High Zr Content for Efficient and Green PET Degradation in Supercritical CO2

“…The transmission peak at 2500–3000 cm –1 attributed to the hydroxyl group stretching vibration in the carboxyl group, and the transmission peak at 1684 cm –1 attributed the stretching vibration to the CO in the carboxyl group . The peaks at 1575, 1509, and 1423 cm –1 represented the vibration of the benzene ring skeleton in TPA . The vibration peak at 1284 cm –1 represented the vibration of C–O .…”

Recent progress of waste plastic upcycling based on multifunctional zeolite catalysts

“…Wherein, NaY zeolite has a high specific surface area and large pore size, provides adjustable acidic and basic sites that favor the reaction, and can be modulated in acidity and basicity when loaded with metal oxides [96] . Thus, Tang et al utilized the MgO/NaY as a modified mesoporous catalyst for the methanolysis of PET wastes, creating an efficient and feasible way to solve the plastic crisis of PET [Figure 9C] [97] . It was demonstrated that both PET conversion and dimethyl terephthalate (DMT) yield increased with rising catalyst basicity [Figure 9D].…”

Recent Advances in the Chemobiological Upcycling of Polyethylene Terephthalate (PET) into Value-Added Chemicals

“…The conversion was influenced by temperature changes; the DMT conversion and TPA yield increased gradually with an increase in temperature. At 160°C, DMT conversion and TPA yield were 33.4 and 21.8%, respectively; at 200°C, the DMT conversion was complete and the rate was 100% (DMT yield = 93.5%) [ 42 ]. Similar to the aminolysis products (BFTA, BHETA, DAA, and DHTA), the methanolysis product, DMT, can be applied to biological upcycling as a substrate after applying a suitable hydrolysis process to produce TPA and EG from DMT.…”