Dioctyl phthalate (DOP) is a kind of main plasticizers in plastic assistant industry whose output is the highest. It is widely used in plastic and rubber prouducts, toys, medical apparatus and instruments due to its excellent characteristics. In this paper, three kinds of multi-phase catalysts were prepared. The effects of preparation condition on structures and properties of the catalysts were investigated. The catalytic performance, selectivity and life of the catalysts in DOP synthesis were also studied.
MCM-41 mesoporous molecular sieves containing heteroatoms (Al, Zn, Ni, Cu, Ce, Fe) (T-MCM-41) were synthesized by direct hydrothermal process. The effects of Si/Al mole ratio, pH value and different heteroatoms incorporation on structures and properties of T-MCM-41 were investigated. The results show that (1) the optimal Si/Al mole ratio is 40 and the optimal pH value is 10.5. (2) T-MCM-41(40) still remains the well-ordered hexagonal mesostructure of MCM-41. Meanwhile, they have high catalytic activity and selectivity in DOP synthesis because heteroatoms incorporation can produce acid centers. Among them, Al-MCM-41(40) shows the highest catalytic activity. When Al-MCM-41(40) was used as the catalyst, whose weight was 2.2 wt.% of the total reaction mixture, the conversion of phthalic anhydride (PA) reaches 98.45% and DOP selectivity reaches 99.13% in 4h.
A series of monolithic catalysts which Sn and SnO are active components, were prepared and and their catalytic performance in synthesis of DOP were studied when nickel foams used as the supports. The effects of current density and electroplating temperature on the electroplating rate were investigated, and the influence of the calcination process and the amount of Sn on the catalytic activities of the catalysts were also studied. The results show that (1) the optimal current density and the temperature is 0.6 A∙dm-2 and 70℃, respectively. (2) the catalytic activity of the catalyst increases after oxidation treatment at 300℃, which attributes to some Sn was oxidized to SnO with higher catalytic activity. (3) the catalytic activities of the monolithic catalysts increase with the amount of Sn increasing. When Sn/Ni-3(300) was used as the catalyst, the conversion of PA reaches 98.02% and DOP selectivity reaches 97.7% in 2.5h.
A series of monolithic catalysts, which SiC foams were used as the supports, were prepared and their catalytic performance in the synthesis of dioctyl phthalate were studied. The effects of calcination process, Ni washcoat and electroplating time on the properties of the catalysts were investigated. The results show that (1) the catalytic activities of the catalysts increase after oxidation, due to the formation of SnO oxidized by Sn. Moreover, the slough caused by Sn melting was avoided because the melting point of SnO is higher than Sn. (2) the addition of Ni washcoat further slows the sloughing speed. (3) these monolithic catalysts have good catalytic activities and selectivities in DOP synthesis. When Sn/Ni/SiC-1(300) was used as the catalyst, the conversion of PA reaches 96.06% and DOP selectivity reaches 97.1% in 2.5h.
The multi-phase catalysts (especially two kinds of monolithic catalysts) prepared in this paper can be easily separated from the reaction mixture and be reused without any treatment.
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