Effect of Preparation Method on the Catalytic Property of Calcined Ca–Al Hydrotalcite for the Synthesis of Ethyl Methyl Carbonate

Abstract

Calcined Ca–Al hydrotalcites were prepared by a clean method (CaAl-1) and coprecipitation (CaAl-2), respectively. Effects of preparation methods on the structure and catalytic property of calcined Ca–Al hydrotalcites were investigated. The samples were characterized by X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG), CO2-programmed temperature desorption method (CO2-TPD), low-temperature N2 adsorption–desorption, and the Hammett indicator method. Compared with CaAl-2, CaAl-1 had a higher specific surface area and surface alkali density, which makes it have relatively higher catalytic activity for transesterification synthesis of ethyl methyl carbonate (EMC). Also, a 50.6% yield of EMC was obtained in the presence of 1.5% CaAl-1 at 100 °C in 1 h. Moreover, the catalytic activity of CaAl-1 showed no remarkable change after five runs.

Effect of Preparation Methods on the Adsorption of Glyphosate by Calcined Ca–Al Hydrotalcite

“…Part of Al 3+ was dissolved in the strong alkaline environment of the co-precipitation system rather than precipitated. In addition, the specific surface area ( S BET ) of Ca-LDO-1 (14.377 m 2 /g) was more than 4 times that of Ca-LDO-2 (3.441 m 2 /g), which was similar to the result reported by previous literature . The average pore sizes of Ca-LDO-1 and Ca-LDO-2 were 3.804 and 3.053 nm, respectively.…”

“…In addition, the surface basicity of the adsorbent had an effect on its adsorption performance of glyphosate since glyphosate is a kind of acidic compound. As shown by previous literature, the surface alkali density of Ca-LDO-1 was higher than that of Ca-LDO-2, which was another reason for the better adsorption of Ca-LDO-1. − Compared with the co-precipitation process of Ca-LDO-2, the clean preparation process of Ca-LDO-1 had the advantages of no wastewater discharge and lower production cost …”

One‐Pot Synthesis of Organic Carbonate from Alcohol and Alkyl Bromide under Low CO2 Pressure

“…When iso-propanol was reacted with bromoethane, 1-bromopropane and 1-bromobutane, the yields of 10-12 were 79 %, 85 % and 84 %, respectively (Table 8, Entries 13-15), which was caused by the steric hindrance. It can be found that steric hindrance had almost no effect on the reaction in the case of iso-butanol, and the yields of the corresponding products 13-15 were higher than 96 % (Table 8, Entries [16][17][18]. The reason for this may be that the branched chain is far away from the hydroxyl group, thus the influence of steric hindrance is weak.…”

“…[14,15] For instance, ethyl methyl carbonate (EMC) as the simplest unsymmetrical carbonate, is widely applied in methylation, ethylation, and methoxycarbonylation reactions. [16] Recently, symmetrical organic carbonates (such as dimethyl carbonate DMC) have been synthesized by transesterification, [17] direct synthesis from CO 2 and alcohols, [18] or one-pot synthesis. [19,20] Compared to symmetrical organic carbonates, unsymmetrical organic carbonates are more difficult to be synthesized.…”

“…Besides, they can be used as excellent solvents, monomers for plexiglass, synthetic lubricants, octane accelerators for gasoline and plasticizers [14,15] . For instance, ethyl methyl carbonate (EMC) as the simplest unsymmetrical carbonate, is widely applied in methylation, ethylation, and methoxycarbonylation reactions [16] …”