CN107774343B

CN107774343B - Catalyst regeneration process

Info

Publication number: CN107774343B
Application number: CN201610772475.1A
Authority: CN
Inventors: 李晗; 胡松; 杨卫胜
Original assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Current assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Priority date: 2016-08-30
Filing date: 2016-08-30
Publication date: 2021-12-28
Anticipated expiration: 2036-08-30
Also published as: CN107774343A

Abstract

The invention aims to provide a method for regenerating a catalyst. The invention adopts a method of regeneration in a catalyst reactor, (1) fresh liquid ammonia is purified by an ammonia still for regeneration; (2) directly pressurizing the gas phase at the top of the ammonia still by 0.02-0.04 MPa without condensing, and heating to remove the regenerated catalyst in the reactor; (3) the catalyst is regenerated by ammonolysis reaction of high-temperature ammonia gas, and the ammonolysis regeneration product of the catalyst mainly comprises mixed ethanolamine, a small part of aminoether and other heavy components; (4) the ammonia still is used for recovering regenerated ammonia gas and catalyst ammonolysis regenerated product. The method is simple and efficient, saves equipment investment, saves energy, reduces consumption, is green and environment-friendly, and can be used for industrial production of ethanolamine prepared by a liquid ammonia method.

Description

Catalyst regeneration process

Technical Field

The invention relates to a regeneration process method of a catalyst, in particular to a process flow for regenerating the catalyst in an ethanolamine production process.

Background

Ethanolamine is an important fine chemical raw material, is a general name of Monoethanolamine (MEA), Diethanolamine (DEA) and Triethanolamine (TEA), has amine and alcohol properties due to the amine and hydroxyl functional groups contained in the molecule, and is widely used in industrial fields such as surfactants, gas absorbents, detergents, intermediates for preparing dyes and synthetic rubbers, and the like. Due to the increasing demand of ethanolamine products at home and abroad, and particularly a certain gap exists between the production and the demand of ethanolamine at home, the new technology for expanding and transforming the original device and developing high efficiency and energy saving is very important.

The industrial production of ethanolamine mainly adopts a process route of reacting Ethylene Oxide (EO) with excessive ammonia, adopts water as a catalyst, and can divide ethanolamine enterprises into four categories according to the concentration of ammonia in the used raw material: 1) the American SD company adopts low-concentration ammonia water as a reaction raw material, and adopts EO, 20-30 wt% of ammonia water (including fresh materials and circulating materials) and circulating ammonia waterMEA reaction (MEA regulation of reaction product structure), NH in fixed bed reactor₃EO is 10:1, the reaction temperature is 100 ℃, the system pressure is 0.5MPa, the products after the reaction are separated and rectified to respectively obtain high-purity MEA, DEA and TEA, the relative contents of the MEA, the DEA and the TEA are respectively 69 wt%, 21 wt% and 10 wt%, the excessive ammonia in the reaction system is recovered by reduced pressure distillation, and the residual ammonia is repeatedly circulated in the form of ammonia water. Because the water content in the system is high, the energy consumption is high in the process of reaction temperature rise and temperature reduction, and the product is easy to dissolve in water and has high dehydration energy consumption. Therefore, although the reaction conditions of the low-concentration ammonia synthesis method are mild, the energy consumption is too high, and the method is gradually eliminated. 2) Dow chemical company adopts medium-high concentration ammonia water as a reaction raw material, the concentration of the ammonia water is 35-50 wt%, the system pressure is 3.5MPa, and the reaction temperature is 115-130 ℃. Dow chemical company adopts the method of high vacuum flash distillation for the first time to retrieve the ammonia in the system, and the product distribution is adjusted by the content of raw material ammonia, and this company adopts the coproduction device of EO and ethanolamine in production. 3) BASF company adopts high-concentration ammonia water as raw material, the concentration of the ammonia water is more than 90 wt%, the system pressure is 10MPa, and NH is generated₃And (2) EO (ethylene oxide)/EO (ethylene oxide) is 15-25: 1, the residence time is 3-30 min, a four-stage heat-insulating pipe reactor is adopted, EO is placed at different nodes in batches and enters the reactor, the reacted materials are decompressed in a flash tower, most of ammonia is evaporated, ammonia is condensed into liquid ammonia and returns, residual ammonia is evaporated at 0.4MPa, and after the liquid ammonia is absorbed into dilute ammonia water by water in a dehydration tower, the dilute ammonia water and the liquid ammonia are prepared into 90% concentrated ammonia water to participate in the reaction. The adoption of high-concentration ammonia has become a trend of an ammonia water method process, and the ammonia water method can obtain a product with balanced composition, but has the problems of more by-products of the product, high separation difficulty, incapability of recovering reaction heat and the like. 4) The Nippon Shokubai company uses liquid ammonia as a raw material and La modified zeolite as a catalyst to generate diethanolamine with high selectivity, and has already been applied industrially. The process conditions are as follows: the reaction temperature is 100-110 ℃, the pressure is 12-15 MPa, and the liquid phase space velocity is 8-10 h^-1When in use, a fixed bed reactor is adopted, and the single-pass weight selectivity of the diethanol amine is about 41 percent; by recycling the monoethanolamine, the weight selectivity of the diethanolamine can reach 81%, and the ethylene oxide can be completely converted, but the catalyst has short operation period(only a few days) is a problem which needs to be solved urgently.

Because of its extremely reactive chemical nature, ethylene oxide tends to undergo self-polymerization at high concentrations to form high boiling point materials such as polyoxyethylene or polyether, or to undergo hydration with hydroxyl-containing materials in the molecule, such as water, alcohols, and the like, to form high boiling point materials such as polyols, polyol ethers, and the like. The side reactions are harmful side reactions for the main reaction-ammonolysis reaction of the ethylene oxide and ammonia, which not only reduces the yield of the main product and wastes EO raw materials, but also seriously influences the quality, especially the chromaticity, of the ethanolamine product and reduces the market competitiveness of the product. In addition, since high boiling point substances generated by the side reaction coat the surface of the catalyst, which is likely to cause the deactivation of the catalyst, it is necessary to regenerate the deactivated catalyst. In order to minimize the influence of catalyst regeneration on the production process and save the running cost and time, it becomes important to realize simultaneous production and regeneration.

The process for producing ethanolamine by the liquid ammonia method has high selectivity, easy product separation, centralized recycling of reaction heat and low energy consumption, is the development direction of ethanolamine technology, and has been reported in documents and patents which relate to reaction equipment and separation processes and have no catalyst regeneration method temporarily.

Disclosure of Invention

The invention provides a new ethanolamine catalyst regeneration process flow aiming at the problems of easy inactivation of the catalyst, high investment on catalyst regeneration equipment and the like in the process for producing ethanolamine by a liquid ammonia method.

In order to solve the above problems, the technical scheme provided by the invention is as follows: a regeneration process method of a catalyst is characterized by comprising the following steps:

(1) purifying fresh liquid ammonia by an ammonia still to obtain regenerated ammonia gas at the top of the ammonia still;

(2) after the regenerated ammonia gas is heated in two stages, the high-temperature regenerated ammonia gas is sent to a reactor to regenerate a catalyst to obtain a regenerated product;

(3) and the product is sent to an ammonia still, and the ethanolamine-containing component is obtained at the bottom of the ammonia still.

In the above technical scheme, preferably, the high-temperature ammonia gas in the step (2) is sent to a reactor to carry out ammonolysis reaction to regenerate the catalyst, and the catalyst is ammonolyzed to generate monoethanolamine, diethanolamine, triethanolamine and a small amount of heavy components.

Impurities such as water, hydrocarbons and the like in the industrial liquid ammonia are easy to be adsorbed on the surface of the catalyst, so that the activity of the catalyst is reduced, and therefore, in the invention, the liquid ammonia is introduced into an ammonia still in advance for impurity removal and purification and then is sent to a regeneration unit.

The catalyst can be regenerated under normal pressure, but in order to reduce the cost, a condenser at the top of the ammonia still uses cooling water instead of chilled water, so the operation pressure at the top of the ammonia still needs to be controlled to be not lower than 1.0MPaG, in order to enable the regenerated product to flow to the ammonia still, the regeneration pressure of the catalyst is not lower than 1.0MPaG, and preferably, the regeneration pressure of the catalyst is 1.6-2.5 MPaG.

The main reason of catalyst deactivation is that the acidic site is covered by impurities such as ammonia ether substances, and the ammonia ether substances are easily decomposed at high temperature, so that the temperature is relatively important for the catalyst ammonolysis regeneration, the temperature is not lower than 250 ℃, the ammonolysis regeneration time is not lower than 8h, most of the ammonia ether substances on the catalyst can be ammonolysis, heavy component residues are reduced along with the prolonging of the time, preferably, the catalyst ammonolysis regeneration temperature is 200-400 ℃, and the regeneration time is 4-30 h.

In the technical scheme, more preferably, the temperature for the ammonolysis regeneration of the catalyst is 250-350 ℃.

In the technical scheme, the regeneration time of the catalyst is more preferably 6-20 h.

In the technical scheme, the most preferable time for catalyst regeneration is 8-16 h.

In the technical scheme, the mass space velocity of the regenerated ammonia gas is preferably 0.1-5 h^-1。

In the technical scheme, more preferably, the mass space velocity of the regenerated ammonia gas is 0.3-1 h^-1。

In the above technical scheme, preferably, the regenerated catalyst is used for ethanolamine production, the conversion rate of ethylene oxide is close to 100%, the selectivity of monoethanolamine and diethanolamine is greater than 90%, and the content of the by-product of amino ether in the product is less than 0.5 wt%.

By adopting the technical scheme, the process can greatly save equipment investment and energy consumption and operating cost in the production process, reduce the production cost, prolong the regeneration period of the catalyst to 3-6 months by using the purified liquid ammonia, prolong the service life of the catalyst to more than 1 year and obtain good technical effects.

Drawings

FIG. 1 is a schematic view of the process of the present invention.

In fig. 1, R101 is a tubular reactor, R102 is an adiabatic fixed bed reactor, T101 is an ammonia still, E101 is a primary ammonia preheater, and E102 is a secondary ammonia preheater. 1 is fresh liquid ammonia, 2 is regenerated ammonia, 3 is low-temperature ammonia, 4 is high-temperature ammonia, 5 is an R101 regenerated product, 6 is an R102 regenerated product, 7 is an ammonia distillation tower kettle product, 8 is monoethanolamine, 9 is diethanolamine, 10 is triethanolamine, and 11 is a heavy component.

In the figure 1, fresh liquid ammonia 1 is purified by an ammonia still T101, the gas phase at the top of the T101 tower is directly pressurized by 0.02-0.04 MPa to form regenerated ammonia 2, the regenerated ammonia 2 is circulated to a regeneration unit, the regenerated ammonia 2 is heated by steam in a primary ammonia preheater E101 to form low-temperature ammonia 3, the regenerated ammonia is heated by an electric heater and a secondary ammonia preheater E102 to form high-temperature ammonia 4, the high-temperature ammonia enters a reactor R101 to react and regenerate a catalyst, an R101 regenerated product 5 enters the reactor R102, an R102 regenerated product 6 is sent to the ammonia still T101, and a product 7 is obtained at the bottom of the T101 tower.

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention in any way.

Detailed Description

[ example 1 ]

The ammonolysis regeneration pressure is 1.8MPaG, the temperature is 280 ℃, the regeneration time is 8h, and the mass space velocity of the regenerated ammonia gas is 0.5h^-1。

The reaction temperature is 90 ℃, the pressure is 8.0MPaG, NH₃The molar ratio/EO was 12.0.

The conversion of ethylene oxide was 99.49%, the selectivity of monoethanolamine and diethanolamine was 92.51%, and the content of the by-product of amino ether was 0.42% by weight.

[ example 2 ]

The ammonolysis regeneration pressure is 2.1MPaG, the temperature is 310 ℃, the regeneration time is 10h, and the mass space velocity of the regenerated ammonia gas is 0.8h^-1。

The reaction temperature is 80 ℃, the pressure is 7.0MPaG, NH₃The molar ratio/EO was 10.0.

The conversion of ethylene oxide was 99.89%, the selectivity of monoethanolamine and diethanolamine was 94.95%, and the content of the by-product of amino ether was 0.31% by weight.

[ example 3 ]

The ammonolysis regeneration pressure is 2.4MPaG, the temperature is 340 ℃, the regeneration time is 12h, and the mass space velocity of the regenerated ammonia gas is 1h^-1。

The reaction temperature is 70 ℃, the pressure is 6.0MPaG, NH₃The molar ratio/EO was 8.0.

The conversion of ethylene oxide was 100%, the selectivity of monoethanolamine and diethanolamine was 97.88%, and the content of the by-product of amino ether was 0.19% by weight.

[ example 4 ]

The ammonolysis regeneration pressure is 2.5MPaG, the temperature is 350 ℃, the regeneration time is 16h, and the mass space velocity of the regenerated ammonia gas is 0.3h^-1。

The conversion of ethylene oxide was 100%, the selectivity of monoethanolamine and diethanolamine was 98.98%, and the content of aminoether by-product was 0.08 wt%.

[ example 5 ]

The ammonolysis regeneration pressure is 1.6MPaG, the temperature is 250 ℃, the regeneration time is 6h, and the mass space velocity of the regenerated ammonia gas is 0.4h^-1。

The conversion of ethylene oxide was 98.99%, the selectivity of monoethanolamine and diethanolamine was 91.05%, and the content of the by-product of amino ether was 0.83% by weight.

[ example 6 ]

The ammonolysis regeneration pressure is 4MPaG, the temperature is 250 ℃, the regeneration time is 4h, and the mass space velocity of the regenerated ammonia gas is 0.5h^-1。

The conversion of ethylene oxide was 96.5%, the selectivity of monoethanolamine and diethanolamine was 85.3%, and the content of the by-product of amino ether was 1.07 wt%.

[ example 7 ]

The ammonolysis regeneration pressure is 2.5MPaG, the temperature is 200 ℃, the regeneration time is 16h, and the mass space velocity of the regenerated ammonia gas is 0.3h^-1。

The conversion of ethylene oxide was 95.3%, the selectivity of monoethanolamine and diethanolamine was 83.9%, and the content of the by-product of amino ether was 1.63% by weight. .

Comparative example 1

Compared with the embodiment 1, the fresh liquid ammonia 1 is not purified by an ammonia still T101, the fresh liquid ammonia is directly pressurized by 0.02-0.04 MPa to be regenerated ammonia 2, the regenerated ammonia 2 is circulated to a regeneration unit, the regenerated ammonia 2 is heated by steam in a primary ammonia preheater E101 to be low-temperature ammonia 3, then is heated by an electric heater and a secondary ammonia preheater E102 to be high-temperature ammonia 4, enters a reactor R101 to react and regenerate a catalyst, an R101 regenerated product 5 enters the reactor R102, an R102 regenerated product 6 is sent to the ammonia still T101, and a product 7 is obtained at the bottom of the T101.

The ammonolysis regeneration pressure was 1.8MPaG,the temperature is 280 ℃, the regeneration time is 8h, and the mass space velocity of the regenerated ammonia gas is 0.5h^-1。

The conversion of ethylene oxide was 98.45%, the selectivity of monoethanolamine and diethanolamine was 90.51%, and the content of the by-product of amino ether was 0.91% by weight.

The catalyst deactivation is accelerated, the regeneration period is shortened, the service life is shortened, and the industrial feasibility is not achieved.

Claims

1. A method for regenerating a catalyst, characterized in that it is carried out according to the following steps:

(3) then the product is sent to an ammonia still, and the component containing ethanolamine is obtained at the bottom of the ammonia still;

the reactors are at least two stages, wherein the first-stage catalytic ammoniation reactor is a tubular fixed bed reactor, and the second-stage catalytic ammoniation reactor is a heat-insulating fixed bed reactor; the regeneration time of the regeneration is 8-16 h, the regeneration pressure is 1.6-2.5 MPaG, and the regeneration temperature is 250-350 ℃.

2. The method for regenerating the catalyst according to claim 1, wherein the high-temperature ammonia gas in the step (2) is sent to a reactor to carry out ammonolysis reaction to regenerate the catalyst, and the catalyst is ammonolyzed to generate monoethanolamine, diethanolamine, triethanolamine and heavy components.

3. The method for regenerating the catalyst according to claim 1, wherein the regenerated ammonia gas in the step (1) is pressurized before entering the step (2).

4. The method for regenerating the catalyst according to claim 1, wherein the mass space velocity of the regenerated ammonia gas is 0.1 to 5 hours^-1。

5. The method for regenerating the catalyst according to claim 4, wherein the mass space velocity of the regenerated ammonia gas is 0.3 to 1 hour^-1。