Synthesis of 1-Methoxy-2-Propanol from Methanol and Propylene Oxide in the Presence of Composition Materials Based on ZIF-8 and Alumina Nanofibers
International Conference "Organic & Hybrid Functional Materials and Additive Technologies"
23-28 Sep 2018
|| Timofeeva Mariya Nikolaevna
, Paukshtis Eugenii Aleksandrovich
, Lukoyanov Ivan Andreevich
, Panchenko Valentina Nikolaevna
, Shefer Kristina Ivanovna
, Gerasimov Evgeny Yurievich
Boreskov Institute of Catalysis SB RAS
Novosibirsk State Technical University
Propylene glycol methyl ether is considered to be important chemical that is widely used as industrial pollution-free solvent with the low toxicity in chemical and cosmetic industry, fine chemicals synthesis in pharmaceutical etc. Although there are several methods for synthesizing propylene glycol methyl ether, the propylene oxide route is the most convenient and industrially feasible in terms of atom-economy and energy efficiency.
Although basic homogenous reaction shows high selectivity to secondary alcohols, they had the drawbacks of separation, liquid waste treating and corrosion problems. Thus, design of heterogeneous catalytic systems has been and still is an important task.
Herein we demonstrate application of novel composites based on zeolitic imidazolate framework (ZIF-8) and alumina nanofibers (Nafen) to synthesize propylene glycol ether. ZIF-8/Nafen composites were synthesized by a solvothermal method. It was found that modification of Nafen by ZIF-8 leads to the exfoliation of alumina nanofibers (Fig. 1). In sample 8.1%ZIF-8/Nafen we can reveal two regions. First region consists of few-layer sheets of nanofibers, where ZIF-8 crystals locate between two sheets of nanofibers. Other region consists of individual nanofibers, where ZIF-8 forms individual homogeneous distributed phase
Figure 1. SEM data of ZIF-8, Nafen and 8.1% ZIF-8/Nafen, and dependence of conversion of PO and selectivity towards (I) on ZIF-8 content in ZIF-8/Nafen
According to DRIFT spectroscopy using CDCl3 as probe molecule, basic sites of Nafen are formed by bridging oxygen atom (Al-O-Al) and -OH groups, whereas Zn-OH groups and N-moieties of nonbridging linkers can act as basic sites of ZIF-8. The increasing ZIF-8 content in composite leads to rise amount of these basic sites. The strength of strongest basic sites of Nafen and ZIF-8 are 955 and 858 kJ/mol, respectively.
The catalytic properties of ZIF-8/Nafen composites were studied in the synthesis of propylene glycol methyl ethers from methanol and propylene oxide (PO) at 2.1 wt.% of catalyst, MeOH/PO molar ratio of 8 and 383 K. It was found that 1-methoxy-2-propanol (I) was the main product with 79.0-93.8% selectivity. Selectivity and reaction rate rose with increasing amount of basic sites that can be adjusted by ZIF-8 content in ZIF-8/Nafen (Fig. 1). Maximal activity and selectivity towards 1-methoxy-2-propanol (93.8%) was observed in the presence of ZIF-8. It was demonstrated that ZIF-8 can be used repeatedly without significant loss of catalytic activity during at least three catalytic cycles.