Study On The Process Of DEHCH Production

As countries are paying more and more attention to the harm of plasticizer to human health, the development of new non-toxic plasticizer gradually become an important research area. Di(2-ethylhexyl)-1,2-cyclohexane di-carboxylate(DEHCH) is a new kind of environmental friendly plasticizer. It has similar function with Dioctyl Phthalate(DOP) in plastic, and it is an ideal substitute of DOP. At present, it has 3 routes to synthesise DEHCH: hydrogenated-esterification route, esterification-hydrogenated route, and cyclization-esterification-hydrogenation route. In this paper, it studied the esterification-hydrogenation route of DEHCH production, the synthesis methods of DOP hydrogenation, and focused on finding the method of separating DEHCH and DOP. It concluded that the two-phase solvent extraction method can separate DEHCH and DOP effectively.It used the ASPEN Plus software to study the process of DEHCH production. From simulating the two-phase solvent extraction experiment, it chose the UNIFAC property method to simulate the process.Through the optimization of extraction tower, it found the optimum operating conditions of the tower: the operating pressure is 100 kPa, the operating temperature is 15℃, the number of theoretical plates is 180, the ratio of light solvent and material to separate is 1.586, the ratio of heavy solvent and material to separate is 2.876. Through the optimization of product tower, it found the optimum operating conditions of the tower: the top pressure is 2kPa, the bottom pressure is 4kPa, number of theoretical plates is 7, reflux ratio is 0.1, feed position is on the 3rd theoretical plate. Through the optimization of the solvent recovery tower, it found the optimum operating conditions of the tower: the top pressure is 2kPa, the bottom pressure is 4kPa, number of theoretical plates is 6, reflux ratio is 0.1, feed position is on the 3rd theoretical plate. Through the optimization of product washing tower, it found the optimum operating conditions of the tower: the operating temperature is 20℃, the operating pressure is 100 kPa, number of theoretical stage is 8, the water consumption is 210kg/h. Through the optimization of circulating washing tower, it found the optimum operating conditions of the tower: the operating temperature is 20℃, the operating pressure is 100 kPa, number of theoretical stage is 9, the water consumption is 100kg/h. Eventually the optimum operation conditions for the process were determined.Then it simulated the process of DEHCH production under the optimized conditions, and simulation results shows that the content of DOP in products is less than 20 mg/kg, the content of water is less than 0.1%, DEHCH quality content is more than 99.9%, which reached the specifications of the product.Finally, it verified the adaptive capacity of the whole process by changing the massflow of stream DOP. The results show that when the flow of stream DOP changes within 2%, it can keep products qualified and process stable.This paper puts forwards an economic and feasible DEHCH production process, which provides DEHCH industrialization a useful theory and reference. And it has very practical and applicable value.