Highly Active MgP Catalyst for Biodiesel Production and Polyethylene Terephthalate Depolymerization

Abstract

A highly active heterogeneous catalyst was designed and employed for two relevant transesterification reactions. i. e. biodiesel production and depolymerization of polyethylene terephthalate (PET). The material was prepared in the presence of pectin by the co‐precipitation method followed by calcination at 600 °C (MgP). MgP is efficient for biodiesel production, with a yield of ≈99 % in 6 h/65 °C, and with a molar ratio methanol: oil of 21 : 1. The reference material (MgR, prepared in absence of pectin) showed a poor catalytic performance in the same experimental conditions. For the methanolysis of PET, 100 % PET conversion was obtained with 3 wt % catalyst, 200 : 1 methanol: PET molar ratio at milder conditions 160 °C/4 h, compared to a 33 % conversion without the presence of a catalyst. The catalyst showed remarkable stability and negligible deactivation after five consecutive runs. Materials were characterized by SEM, XRD, IR, TGA, and BET.

Depolymerization within a Circular Plastics System

“…The calcination pretreatment was energy intensive; 700 °C for 4 h. A common feature of heterogeneous systems is high operating temperature (200 °C), likely required to ensure PET dissolution and binding to the catalyst surface. Magnesium oxide and magnesium–pectin catalysts have been reported to give >90% DMT yields along with catalyst recyclability. , A multistep but mild preparation of ZnO nanoparticles was reported by Du et al, with use of the nanoparticles demonstrating excellent DMT yields (>95%) after just 15 min, even at 10 g PET loading …”

“…Magnesium oxide and magnesium−pectin catalysts have been reported to give >90% DMT yields along with catalyst recyclability. 162,163 A multistep but mild preparation of ZnO nanoparticles was reported by Du et al, with use of the nanoparticles demonstrating excellent DMT yields (>95%) after just 15 min, even at 10 g PET loading. 164 A combined LCA and material flow analysis compared the impacts of virgin-PET production, methanolysis, hydrolysis, and mechanical recycling.…”

Chemical recycling of polyester textile wastes: shifting towards sustainability

“…Recent efforts demonstrated the possibility to use bio-based catalyst with decent results. Laldinpuii et al demonstrated that bamboo leaf ash use at 200 °C for 2 h allows a decent retrieving monomers yield (78%), 151 and Gangotena et al also used pectin derivatives to obtain an almost full depolymerisation at 160 °C for 4 h. 152 Zeolites can also present nice alternatives to the classical metal-based catalysts, showing similar performances (>90% within 30 min at 200 °C, MgO/NaY catalyst). 153 Ionic liquids also work pretty well in this temperature/time range, 154,155 even focusing originally on fibres waste.…”

Copper-supported catalysts for sustainable PET depolymerization: a cost-effective approach towards dimethyl terephthalate (DMT) production

“…34 For example, the demand for DMT has been steadily increasing across various industries, such as packaging, construction and electronics. 35 Therefore, the methanolysis of PET serves as an effective technology to achieve the high-value recycling of PET waste plastics.…”