Synthesis of Propylene Glycol Monomethyl Ether Over Mg/Al Hydrotalcite Catalyst

Abstract

Mg-Al hydrotalcites with different Mg/Al molar ratios were prepared and characterized by XRD, FT-IR, SEM and BET analyses. The calcined hydrotalcite with Mg/Al molar ratio of 4.0 (LDO Mg/Al 4.0) exhibited the highest catalytic activity in the synthesis of propylene glycol methyl ether (PM). The catalytic activity relating to the amount of the basic sites and crystallinity depended on the Mg/Al molar ratio. The optimal equilibrium of acidbase property and high crystallinity made the LDO Mg/Al 4.0 an excellent catalyst in the reaction. Etherification of propylene oxide (PO) with methanol over the LDO Mg/Al 4.0 was researched. The optimized reaction conditions were as follows: 140°C, catalyst amount 0.9 wt%, methanol/PO molar ratio 4.0 and 6 h. The PO conversion and PM selectivity were 93.2 and 97.4%, respectively. Above all, almost all the PM was 1-methoxy-2-propanol, for no 2-methoxy-1-propanol was detected by GC analysis in the reaction products, and the catalyst could be reused for five times.

Mg–Al hydrotalcites as solid base catalysts for alcoholysis of propylene oxide

“…In our preliminary work, it was found that Mg-Al-CO 3 hydrotalcites (Mg-Al LDHs) showed the high activity and selectivity to the desired product (MP) in the synthesis of PGME [13]. In the present work, Mg-Al LDHs were prepared by urea decomposition and coprecipitation methods.…”

“…Though both basic and acidic sites are present in the Mg-Al LDHs, it was reported that the synthesis of 1-methoxy-2-propanol should be closely related to the basic sites with moderate strength [13]. The base strength (H − ) of a solid surface was defined as the ability of converting an adsorbed electrically neutral acid into its conjugate base.…”

“…Layered double hydroxides had recently received much attention in view of their potential usefulness as adsorbents, as anion exchangers, and most importantly as base catalysts [8]. It had been used in aldol-type condensations [8], Knoevenagel condensations [9], Michael additions [10] and Claisen-Schmidt condensations [11] with appreciable rates and selectivity, especially in the synthesis of PGME [12,13].…”

Structures of LDHs Intercalated with Ammonia and the Thermal Stability for Poly(vinyl chloride)

“…If the charge density of anion was low, the interactions between anions and positively charged layers was weak, and then the layer spacing was large. d(110) reflected the atomic arrangement density of the (110) crystal plane [8].…”

Mg–Fe mixed oxides as solid base catalysts for the transesterification of microalgae oil

“…[12][13][14][15] The catalytic activity has been determined by not only the basicity of It is found that the mixed oxides (LDO) obtained by calcination of the hydrotalcites are more 1 effective catalysts with stronger basic properties compared to the LDH precursors in the 2 transesterification reactions. 14,15,20,21 The catalytic activity shows a correlation not only with the 5 basicity which is dependent on the preparation method. 14,15,20,21 The catalytic activity shows a correlation not only with the 5 basicity which is dependent on the preparation method.…”