Oxidative Esterification of Methacrolein to Methyl Methacrylate over Gold Nanoparticles on Hydroxyapatite

Abstract

The catalytic production of methyl methacrylate through the direct oxidative esterification of methacrolein is important in terms of green chemistry and sustainable development. In the present work, Au nanoparticles supported on three needle‐like, lamella‐like, and rodlike hydroxyapatites were synthesized. We demonstrated that needle‐like hydroxyapatite could facilitate the higher dispersion of Au species because of its high specific surface area, and the strong interaction between the Au nanoparticles and the support resulted in the formation of more surface defects because of the existence of partially encapsulated Au particles by the needle‐like hydroxyapatite. The surface defects were related closely to the generation of strong basic sites. Compared with the other two materials, the Au supported on the needle‐like hydroxyapatite catalyst, which had a large amount of surface acid–base sites, exhibited a much higher catalytic activity and selectivity to methyl methacrylate in the direct oxidative esterification of methacrolein with methanol under mild reaction conditions (i.e., ambient pressure, low reaction temperature of 70 °C, and low methanol/aldehyde ratio of 8:1). The superior catalytic performance of the Au supported on needle‐like hydroxyapatite catalyst was attributable to a cooperative effect between abundant acid–base sites for the preferential chemisorption of methacrolein and highly dispersed active Au species for the favorable formation of β‐hydride and oxygen activation. The present findings open a new and promising route for the practical production of methyl methacrylate using high‐performance hydroxyapatite‐supported metal catalyst systems.

Ionic‐Liquid‐Modified Porous Au/CeMnOx Nanorods for Methyl Methacrylate (MMA) Synthesis via Direct Oxidative Esterification

“…This negative shift illustrated a negative charge on the gold atoms, which possibly due to the transfer of electrons from the supports to the Au atoms. This confirmed the strong interaction between nano‐Au particles and PNCM‐12 support . It can be clearly seen in Figure b that Au/PNCM‐12 and Au/PNCM‐14 catalyst contain more than one type of oxygen species.…”

“…This confirmed the strong interaction between nano-Au particles and PNCM-12 support. [28,29] It can be clearly seen in Figure 4b that Au/PNCM-12 and Au/PNCM-14 catalyst contain more than one type of oxygen species. Three peaks with different binding energies were found by fitting the peaks of O 1s.…”

Structure‐Activity Relationships of Au/Al2O3 Catalyst for the Selective Oxidative Esterification of 1,3‐Propanediol and Methanol

“…Based on the reaction pathway for the oxidative esterification of alcohols and aldehydes with methanol in the previous reports and combined with the above results of characterizations and catalytic tests, a possible mechanism for the Au/Al 2 O 3 ‐catalyzed oxidative esterification of 1,3‐proanediol is illustrated in Schemes −3. The one‐pot aerobic conversion of 1,3‐proanediol into methyl esters involves three steps.…”

Cyanide‐Free One‐Pot Synthesis of Methacrylic Esters from Acetone

“…The third process is the C2 process (Scheme c): First, methyl propionate is made from ethylene, carbon monoxide, and methanol. Subsequently, methyl propionate reacts with formaldehyde and then dehydration results in the formation of MMA . As an alternative route to methacrylate esters, here we propose the use of chloroform in place of hydrogen cyanide in Scheme a as a C1 source.…”

“…Subsequently,m ethyl propionate reacts with formaldehyde and then dehydration results in the formation of MMA. [4] As an alternative route to methacrylate esters, here we propose the use of chloroformi np lace of hydrogen cyanidei n Scheme 1a as aC 1s ource. In 1948, Weizmann et al reported the reaction of 1,1,1-trichloro-2-methyl-propan-2-ol (acetonechloroform, 2)w ith potassiumh ydroxide in alcohol to form aalkoxyp ropanoica cid 3 (Scheme 1d).…”