Method for increasing UV transmittance of ethylene glycol

Abstract

The present invention provides a method for increasing the UV transmittance of ethylene glycol. The method uses an ethylene glycol solution and hydrogen as raw materials, and uses an alloy catalyst comprising nickel, one or more rare-earth elements, tin, and aluminum, the contents thereof in parts by weight being 10-90, 1-5, 1-60, and 5-9, respectively. The method of the present invention uses an inexpensive, stable-in-aqueous-phase, carrier-free alloy as a catalyst, and continuously adds hydrogen to reduce unsaturated impurities in ethylene glycol. In application of the method of the present invention in continuous industrial-scale production, the use of this type of alloy catalyst could be especially significant for the achievement of long-term system stability and control of production costs.

Claims

1. A method for improving the ultraviolet transmittance of ethylene glycol, the method comprising contacting an ethylene glycol solution and hydrogen with one of the following catalysts: (i) an unsupported metal alloy catalyst consisting of nickel, one or more rare earth element, tin and aluminum, the contents of the components in parts by weight being 10-90 parts, 1-5 parts, 1-60 parts and 5-9 parts respectively, (ii) an unsupported catalyst consisting of nickel, one or more rare earth element, tin, aluminum and tungsten, the contents of the components in parts by weight being 10-90 parts, 1-5 parts, 1-60 parts, 5-9 parts and 1-90 parts respectively; (iii) an unsupported catalyst consisting of nickel, one or more rare earth element, tin, aluminum, tungsten and molybdenum, the contents of the components in parts by weight being 10-90 parts, 1-5 parts, 1-60 parts, 5-9 parts, 1-90 parts and 0.5-20 parts respectively; or (iv) an unsupported catalyst consisting of nickel, one or more rare earth element, tin, aluminum, tungsten, molybdenum and boron or phosphorous, the contents of the components in parts by weight being 10-90 parts, 1-5 parts, 1-60 parts, 5-9 parts, 1-90 parts, 0.5-20 parts and 0.01-5 parts respectively.

2. The method as claimed in claim 1, characterized in that the amount used of the catalyst is 0.01-10 times the mass fed of the ethylene glycol solution.

3. The method as claimed in claim 1, characterized in that the method further comprises the addition of ethylene glycol solution and metal alloy catalyst at any time; the amount added of the metal alloy catalyst is: 0.01-5 kg of metal alloy catalyst added per 1000 kg of ethylene glycol fed.

4. The method as claimed in claim 1, characterized in that the method has a reaction system temperature of 50-200 C.

5. The method as claimed in claim 4, characterized in that the method has a reaction pressure of 0.1-12 MPa, and a reaction time of 10 min or more.

6. The method as claimed in claim 5, characterized in that the reaction system temperature is 80-150 C., the reaction pressure is 0.5-10 MPa, and the reaction time is 0.5-3 h.

7. The method as claimed in claim 1, characterized in that the ethylene glycol solution has a concentration of 5-90 wt.

8. The method as claimed in claim 1, wherein catalyst (i) or (ii) is selected from the group consisting of Ni80La1Sn30Al5, Ni10Sm5Sn3Al9W70Mo5, Ni70Ce1Sn50Al7W5Mo1B5, Ni90Ce3Sn60Al9W20Mo5B1, Ni10Sm5Sn10Al9W90, Ni90Ce3Sn60Al9W20Mo20P0.01 and Ni80La1Ce0.55n30Al5.

9. The method as claimed in claim 4, wherein the method has a reaction system temperature of 80-150 C.

10. The method as claimed in claim 6, wherein the reaction time is 0.5-2 hours.

11. The method as claimed in claim 7, wherein the ethylene glycol solution has a concentration of 50-85 wt %.

Description

DESCRIPTION OF THE ACCOMPANYING DRAWING

(1) Particular embodiments of the present invention are explained in further detail below with reference to the accompanying drawing.

(2) FIG. 1 shows an ethylene glycol hydrogenation process flow.

PARTICULAR EMBODIMENTS

(3) In order to explain the present invention more clearly, the present invention is explained further below with reference to preferred examples and the accompanying drawing. Similar components in the drawing are represented by identical reference labels. Those skilled in the art should understand that the content specifically described below is illustrative but non-limiting, and should not be used to restrict the scope of protection of the present invention.

Example 1

Preparation of Metal Alloy Catalyst

(4) For the metal alloy catalyst of the present invention, a chemical reduction method or an electrolytic deposition method may be used to directly prepare an active metal powder having a high specific surface area, or a smelting method is first used to form a metal alloy, then a mechanical pulverizing method or atomization method etc. is used to form a metal powder, and finally a conventional Raney nickel catalyst activation method is used to form an active metal powder. For example, nickel, a rare earth element, tin, aluminum, tungsten, molybdenum, and boron or phosphorus are added to a smelting furnace, the contents thereof in parts by weight being 10-90 parts, 1-5 parts, 1-60 parts, 5-9 parts, 1-90 parts, 0.5-20 parts and 0.01-5 parts respectively, the temperature is increased to 1500-2000 C., then the temperature is reduced, thorough mechanical stirring is carried out to achieve uniformity and then the furnace is emptied, to obtain a metal alloy. A hammer mill is used to pulverize the metal alloy into a metal powder, and the metal powder is immersed in a 20 wt %-25 wt % aqueous sodium hydroxide solution for 1-2 hours at 70-95 C., to form an active metal powder having a high specific surface area.

(5) A metal alloy catalyst Ni80La1Sn30Al5 (indicating a metal alloy composition of 80 parts Ni+1 part La+30 parts Sn+5 parts Al, similarly below), a metal alloy catalyst Ni10Sm5Sn3Al9W70Mo5, a metal alloy catalyst Ni70Ce1Sn50Al7W5Mo1B5, a metal alloy catalyst Ni90Ce3Sn60Al9W20Mo5B1, a metal alloy catalyst Ni10Sm5Sn10Al9W90, a metal alloy catalyst Ni90Ce3Sn60Al9W20Mo20P0.01 and a metal alloy catalyst Ni80La1Ce0.5Sn30Al5 are separately prepared.

Example 2

(6) 6 L of water and 1000 g of the metal alloy catalyst Ni80La1Sn30Al5 are added to a 10 L reaction kettle while stirring. The reaction kettle is sealed, hydrogen is passed in at the rate of 100 L/h at atmospheric pressure to replace air in the reaction kettle for 5 hours, then the hydrogen pressure is increased to 10 MPa, hydrogen continues to be passed in for 5 hours, the temperature of the reaction kettle is increased to 80 C., and continuous feeding begins. The feed composition is: 50 wt % ethylene glycol and 50 wt % water; the feeding rate is 3 L/h. The residence time of the aqueous ethylene glycol solution in the reaction kettle is 2 hours. Hydrogen and a reaction liquid resulting from a reaction flow out of the reaction kettle through a filter and enter a condensation tank; the discharge rate of the reaction liquid is 3 L/h; the reaction liquid is cooled and then discharged from the bottom of the condensation tank, to obtain an outflowing liquid. The outflowing liquid enters a rectification separation system, and water and ethylene glycol are separately obtained. A sample is taken at the bottom of the condensation tank, and a UV/vis spectrophotometer is used to detect the UV transmittance of the ethylene glycol. See table 1 for the results.

(7) The metal catalyst of the present invention can ensure that the reaction system continuously operates for 1000 hours or more, and the UV transmittance of ethylene glycol is still stable.

Example 3

(8) The metal alloy catalyst is Ni10Sm5Sn3Al9W70Mo5, and the amount added is 5000 g. The feed composition is: 70 wt % ethylene glycol. The reaction pressure is 0.5 MPa, the reaction temperature is 150 C., and the other operating conditions are the same as in example 2. See table 1 for results.

(9) The metal catalyst of the present invention can ensure that the reaction system continuously operates for 1000 hours or more, and the UV transmittance of ethylene glycol is still stable.

Example 4

(10) The metal alloy catalyst is Ni70Ce1Sn50Al7W5Mo1B5, and the amount added is 500 g. The feed composition is: 85 wt % ethylene glycol. The reaction pressure is 12 MPa, the reaction temperature is 170 C., and the other operating conditions are the same as in example 2. See table 1 for results.

(11) The metal catalyst of the present invention can ensure that the reaction system continuously operates for 1000 hours or more, and the UV transmittance of ethylene glycol is still stable.

Example 5

(12) The metal alloy catalyst is Ni90Ce3Sn60Al9W20Mo5B1, and the amount added is 1000 g. The feed composition is: 75 wt % ethylene glycol. The reaction pressure is 5 MPa, the reaction temperature is 90 C., and the other operating conditions are the same as in example 2. See table 1 for results. After 1000 hours of catalyst operation, the UV transmittance of ethylene glycol is still stable.

Example 6

(13) The metal alloy catalyst is Ni90Ce3Sn60Al9W20Mo5B1, and the amount added is 5000 g. The feed composition is: 70 wt % ethylene glycol, the reaction pressure is 1 MPa, the reaction temperature is 100 C., and the other operating conditions are the same as in example 2. See table 1 for results.

(14) The metal catalyst of the present invention can ensure that the reaction system continuously operates for 1000 hours or more, and the UV transmittance of ethylene glycol is still stable.

Example 7

(15) The alloy main catalyst is Ni10Sm5Sn10Al9W90, and the amount added is 180 g. The feed composition is: 70 wt % ethylene glycol. The reaction pressure is 8 MPa and the reaction temperature is 140 C. The other operating conditions are the same as in example 2. See table 1 for results.

(16) The metal catalyst of the present invention can ensure that the reaction system continuously operates for 1000 hours or more, and the UV transmittance of ethylene glycol is still stable.

Example 8

(17) The alloy catalyst is Ni90Ce3Sn60Al9W20Mo20P0.01, and the amount added is 5 g. The feed composition is: 85 wt % ethylene glycol. The reaction pressure is 3 MPa and the reaction temperature is 120 C. The other operating conditions are the same as in example 2. See table 1 for results.

(18) The metal catalyst of the present invention can ensure that the reaction system continuously operates for 1000 hours or more, and the UV transmittance of ethylene glycol is still stable.

(19) TABLE-US-00001 TABLE 1 Effect of hydrogenation treatment of ethylene glycol on UV transmittance Water content of ethylene Pressure Temp. glycol UV transmittance (%) (MPa) ( C.) (%) 220 nm 274 nm 350 nm Example 2 10 80 50 After 47 89 100 hydrogenation Before 36 81 100 hydrogenation Example 3 0.5 150 30 After 67 96 100 hydrogenation Before 46 90 100 hydrogenation Example 4 12 170 15 After 63 95 100 hydrogenation Before 50 90 100 hydrogenation Example 5 5 90 25 After 76 100 100 hydrogenation Before 62 92 100 hydrogenation Example 6 1 100 30 After 25 70 86 hydrogenation Before 0.2 16 86 hydrogenation Example 7 8 140 30 After 52 83 100 hydrogenation Before 3 75 86 hydrogenation Example 8 3 120 15 After 65 95 100 hydrogenation Before 36 88 100 hydrogenation

(20) Clearly, the above examples of the present invention are merely examples given for the purpose of clearly explaining the present invention, and do not limit the embodiments of the present invention. Those skilled in the art could still make other changes or alterations in various forms, on the basis of the above explanation. It is not possible to set out all embodiments here exhaustively. All obvious changes or alterations derived from the technical solution of the present invention shall still fall within the scope of protection of the present invention.