Stable Organic Titanium Catalysts and Reactive Distillation Used for the Transesterification of Dimethyl Carbonate with Phenol

Abstract

The transesterification of dimethyl carbonate with phenol to methyl phenyl carbonate (MPC) was investigated on novel catalysts such as titanium diisopropoxide bis(ethyl acetoacetate) and titanium dibutoxide bis(ethyl acetoacetate) in a closed batch reactor at 185-206°C under high pressure. The produced methanol could be removed efficiently by reactive distillation in order to overcome the equilibrium. The prepared catalysts have higher resistance to water than titanium alkoxides. Phenol conversion as high as 86.4 % with an MPC selectivity of 99.4 % was achieved under optimal reaction conditions within 9 h. Most of the catalytic activity was retained after repeated use for ten times.

Efficient Advanced Oxidation Process (AOP) for Photocatalytic Contaminant Degradation Using Exfoliated Metal-Free Graphitic Carbon Nitride and Visible Light-Emitting Diodes

“…Figure 9 shows the influence of pH on phenol degradation. The photodegradation efficiency of phenol at acidic pH (2)(3)(4)(5) was better than at basic pH (9)(10)(11)(12). Almost 97% of phenol degradation was achieved in 60 min of reaction time at acidic pH compared with 100% for natural pH in 90 min and 80% at basic pH in 180 min, a similar pH dependency was shown in the literature [47,54].…”

“…Polluted water is harmful to human health and the ecosystem [1,2]. In this context, several efforts have been made to completely remove phenolic contaminants from wastewater using conventional methods, including adsorption [3,4], distillation [5], biological treatments [6], and chemical oxidation [7]; however, these techniques have their demerits. Heterogeneous photocatalysis has proven to be an effective and feasible method for removing organic contaminants, producing CO 2 and mineral salts as byproducts [8].…”

Diphenyl Carbonate: Recent Progress on Its Catalytic Synthesis by Transesterification

“…The general transesterification reaction equation of phenol and DMC is [14,[16][17][18] shown by (1) in Figure 1: This reaction includes the following steps: DMC reacts with phenol to form methyl phenyl carbonate (MPC) through transesterification, shown by (2) in Figure 1. MPC and phenol are subjected to the transesterification reaction again to generate DPC, shown by (3) in Figure 1, or MPC undergoes a self-disproportionation reaction to generate DMC and DPC, shown by (4) in Figure 1.…”

“…Titanium alkoxides are highly susceptible to hydrolysis, leading to the formation of insoluble TiO 2 and the loss of catalytic activity. To overcome this drawback, Fang et al [17] proposed the complexation of titanium alkoxides with acetylacetone to substitute the alkoxy groups of titanium alkoxides with acac, aiming to enhance their water resistance. The structure of the prepared complex is shown in Figure 4.…”