CN115837277A - Regeneration method of gold catalyst in vinyl chloride production process - Google Patents

Abstract

The invention provides a regeneration method of a gold catalyst in the production process of vinyl chloride, and relates to the technical field of catalyst regeneration. The regeneration method comprises the following steps: (1) judging the deactivation degree of the gold catalyst; (2) determining the degree of deactivation of the gold catalyst; ‑25% activation and regeneration at any site; (3) Use inert gas to purging at activation temperature; (4) After purging, pass activation gas to activate; (5) After activation, pass HCl and acetylene (6) When the outlet acetylene content returns to the content before regeneration, repeat steps (1)-(4). In addition, the regeneration method can also be activated and regenerated during the production process. The regeneration process in the present invention is simple, without unloading and immersing the catalyst, which can effectively reduce the loss of active components in the regeneration process and improve the gold recovery rate; at the same time, the activity of the gold catalyst can be significantly restored, metal sintering can be inhibited, and the carbon deposition resistance of the catalyst can be improved. The production cost is greatly reduced.

Description

A kind of regeneration method of gold catalyst in vinyl chloride production process

technical field

The invention relates to the technical field of catalyst regeneration, in particular to a method for regenerating gold catalysts in the vinyl chloride production process.

Background technique

Polyvinyl chloride resin (PVC) is a general-purpose synthetic resin, a polymer compound polymerized by vinyl chloride monomer (VCM), which has excellent physical, chemical and mechanical properties, and is used in industry, construction, agriculture, It is widely used in packaging, electric power and other industries. The production methods of vinyl chloride mainly include acetylene method, ethane method and ethylene method. However, the acetylene method has always used the highly toxic mercury chloride catalyst. The product affects the product quality of VCM and seriously restricts the sustainable development of the acetylene process. In the mercury-free catalytic system for the synthesis of vinyl chloride by acetylene hydrochlorination, the activated carbon-supported gold catalyst has high catalytic activity and selectivity. Although it is expensive and has poor stability, the sublimation phenomenon of the gold catalyst is not significant and the loss is small. It is easy to recover and reactivate, so the gold catalyst is considered to be the most promising catalyst to replace mercuric chloride in the synthesis of vinyl chloride by hydrochlorination of acetylene.

In the research process of mercury-free catalysts for acetylene hydrochlorination, activated carbon-supported gold catalysts are considered to be the most potential industrial catalysts, which have the advantages of high activity, high stability and high selectivity. At present, there are few researches on the regeneration method of carbon-supported noble metal catalysts in this reaction system at home and abroad. When the reaction temperature is low, the activity of the gold catalyst is relatively low, and carbon deposition is the main reason for the deactivation of the catalyst. During the low-temperature reaction process of acetylene hydrogen chloride reaction to generate vinyl chloride, part of acetylene is polymerized to generate aromatic hydrocarbons or their derivatives. These substances have high boiling points and are not volatile. They gradually accumulate and accumulate to slowly cover the pores and active sites on the surface of the catalyst. , resulting in a gradual decrease in the activity and selectivity of the catalyst. At the same time, as the catalyst is wrapped by carbon deposits, the catalyst particles become more viscous and compacted, resulting in a significant decline in the performance of the catalyst and making it unusable, reducing production efficiency and increasing operating costs. When the temperature is high, high-valence gold (Au ³⁺ , Au ⁺ ) is reduced to zero-valence gold (Au ⁰ ) and inactivated, thereby losing the value of industrial applications. On the one hand, because acetylene is a reducing gas, it will reduce Au ³⁺ to Au ⁰ and deactivate it. At the same time, activated carbon itself is also reducing. On the other hand, because the active component is AuCl ₃ , its own Decomposition occurs to generate AuCl and Cl ₂ , AuCl is unstable and disproportionation reaction occurs to generate Au ⁰ and Cl ₂ , zero-valent gold has poor reaction performance to acetylene hydrochlorination to synthesize vinyl chloride. Based on this deactivation mechanism, Chinese patent CN202111466297.7 discloses a regeneration method of a mercury-free noble metal catalyst for acetylene hydrochlorination. The mercury-free noble metal catalyst is put into an oxidizing agent such as hydrogen peroxide, which greatly improves the recovery rate of the initial conversion rate. , so that the catalytic activity of the catalyst can be restored to the original performance to the greatest extent. CN201910947836.5 discloses a method for regenerating a gold-carbon catalyst used in acetylene hydrochlorination. In this method, the catalyst activity can be well recovered after the catalyst is dried, roasted, and oxidized.

However, the existing regeneration technologies basically require immersion oxidation with strong oxidizing reagents in order to effectively restore the catalyst activity. However, the industrial production process is a continuous process. If the catalyst in the reactor is unloaded for soaking and regeneration operation, the operation complexity will be greatly increased, and the wear loss during the catalyst loading and unloading process will be increased. Moreover, the catalyst is used for more than one year in industrial production, and long-term operation will cause serious carbon deposition, hardening, and pulverization of the catalyst. If a highly oxidizing reagent is used to regenerate the catalyst at this time, it will inevitably The catalyst particles are broken and part of the active components are dissolved and taken away by the oxidizing reagent, which reduces the loading capacity of the active components and the subsequent recovery rate, and increases the cost of the catalyst. At the same time, oxidizing reagents are also prone to produce industrial waste, resulting in additional operating costs and environmental protection costs.

Contents of the invention

Aiming at the problems existing in the prior art, the present invention provides a regeneration method of gold catalyst in the production process of vinyl chloride. The regeneration method is simple in process, high in recovery rate and low in cost, and can be activated and regenerated in the production process without affecting Production operation stability.

To achieve the above object, the technical scheme adopted in the present invention is as follows:

The invention provides a kind of regeneration method of gold catalyst, comprises the following steps:

(1) judge the deactivation degree of the gold catalyst;

(2) Activation and regeneration at any point within the range of 2-25% of the outlet acetylene content;

(3) Use an inert gas to purge at the activation temperature;

(4) After the purging is completed, activate the activation gas;

(5) After finishing the activation, feed HCl and acetylene;

(6) When the outlet acetylene content returns to the content before regeneration, repeat steps (1)-(4).

Further, the inert gas in step (3) includes nitrogen and/or argon.

Further, the activation temperature in step (3) is 50-300°C, and the purging time is 0-48h.

Further, the space velocity of the inert gas is 10-50h ^-1 .

Further, the activation gas in step (4) includes one or more of Cl ₂ , NO, N ₂ O and HCl.

In some specific embodiments, the regeneration method of the gold catalyst comprises the following steps:

(1) Judging the degree of deactivation of the gold catalyst by the content of acetylene at the outlet;

(2) Activation and regeneration at any point within the range of 2-25% of the outlet acetylene content;

(3) shut down the acetylene and hydrogen chloride gas, use inert gas to purge at the activation temperature, the activation temperature is 50-300°C, the purge time is 0-48h, and the inert gas space velocity is 10-50h ⁻¹ ;

(4) After the inert gas purging is completed, activate the activation gas with a concentration of 50%-100%, the space velocity of the activation gas is 10-50h ^-1 , and the difference between the outlet activation gas concentration and the initial concentration is stable at 1% within half an hour Within, the activation is terminated;

(5) Feed in the raw materials HCl and acetylene, detect the change of the acetylene content at the outlet, and carry out normal production.

(6) When the content of acetylene at the outlet returns to the content before regeneration, perform steps (2)-(5) again.

Further, the present invention also provides another regeneration method of gold catalyst, comprising the following steps:

S1: Judging the deactivation degree of the gold catalyst;

S2: Activation and regeneration at any point within the range of 2-25% of the outlet acetylene content;

S3: Activation by passing through the activation gas;

S4: stop the activation gas feeding;

S5: When the outlet acetylene content returns to the content before regeneration, repeat steps S1 to S4.

Further, the activation gas in step S3 includes one or more of Cl ₂ , NO, N ₂ O and HCl, preferably HCl.

Further, the space velocity of the activated gas in step S3 is 10-50 h ^-1 , and the volume concentration is 95-100%.

Further, the activation time in step S3 is 0-48h.

Further, the HCl gas in step S3 is introduced from the measuring line pipeline during the operation of the production device.

Further, the location of activation and regeneration in step (2) or S2 is a single site or more than one site.

In some specific embodiments, the regeneration method of the gold catalyst comprises the following steps:

S1: Judging the degree of deactivation of the gold catalyst by the content of acetylene at the outlet;

S2: Activation and regeneration at any point within the range of 2-25% of the outlet acetylene content;

S3: During the operation of the production device, inject HCl gas with a concentration of 95%-100% from the side line pipeline for activation for 24 hours, the HCl gas space velocity is 10-50h ^-1 , and the activation time is 0-48h;

S4: stop the HCl feed, detect the change of the acetylene content at the outlet, and carry out normal production;

S5: When the content of acetylene at the outlet is restored to the content before regeneration, the operations of steps S1 to S4 are performed again.

Further, the regeneration method in the present invention can be applied in the production process of vinyl chloride.

The technical effect that the present invention obtains is:

(1) The regeneration process of the present invention is simple, and the scheme does not need to unload and soak the catalyst, which can effectively reduce the loss of active components in the regeneration process and improve the gold recovery rate;

(2) Significantly restore the activity of the gold catalyst, inhibit metal sintering and improve the anti-coking performance of the catalyst, increase the conversion rate, improve the service life of the catalyst, and greatly reduce the production cost.

(3) It can be activated and regenerated during the production process without affecting the stability of production operation;

(4) the present invention is carried out to certain time when reaction, and when the activity of catalyzer is reduced to some extent, at first use inert gas to purge the coke and toxic substance agglomerated on catalyzer to make it loose, realize the preliminary cleaning to catalyzer surface and channel; Then, one or more of the activated gas Cl ₂ , NO, N ₂ O and HCl is introduced into the reaction system to oxidize Au0 to an ion state, effectively restore the catalyst activity, and further purge to remove the accumulation in the deactivated catalyst. carbon to partially regenerate the catalyst.

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

Before further describing the specific embodiments of the present invention, it should be understood that the protection scope of the present invention is not limited to the following specific specific embodiments; it should also be understood that the terms used in the examples of the present invention are to describe specific specific embodiments, It is not intended to limit the protection scope of the present invention.

When the examples give numerical ranges, it should be understood that, unless otherwise stated in the present invention, the two endpoints of each numerical range and any value between the two endpoints can be selected. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is worth noting that the raw materials used in the present invention are all common commercially available products, so their sources are not specifically limited.

Example 1

A method for regenerating a gold catalyst, comprising the following steps:

(1) Judging the degree of deactivation of the gold catalyst by the content of acetylene at the outlet;

(2) When the outlet acetylene content is 3%, any site is activated and regenerated;

(3) Shutdown (that is, the reactor stops running) closes acetylene and hydrogen chloride gas, and uses _N to purge at the activation temperature. The activation temperature is 120° C., the purge time is 12 h, and the space velocity of the inert gas is 30 h ⁻¹ ;

(4) After the inert gas purging is completed, HCl with a concentration of 95% is introduced to activate for 24 hours, the space velocity of the activated gas is 40h ^-1 , and the difference between the concentration of the activated gas at the outlet and the initial concentration is stabilized within 1% within half an hour, and the activation is terminated;

(5) Feed in the raw materials HCl and acetylene, detect the change of the acetylene content at the outlet, and carry out normal production.

(6) Start up (that is, the reactor is turned on) to detect the regeneration effect. When the outlet acetylene content returns to 3%, perform steps (2)-(5) again to detect the regeneration effect.

Example 2

A method for regenerating a gold catalyst, comprising the following steps:

(1) Judging the degree of deactivation of the gold catalyst by the content of acetylene at the outlet;

(2) When the outlet acetylene content is 3%, any site is activated and regenerated;

(3) Shut down and close the acetylene and hydrogen chloride gas, use _N to purge at the activation temperature, the activation temperature is 140°C, the purge time is 12h, and the space velocity of the inert gas is 30h ⁻¹ ;

(4) After the inert gas purging is completed, HCl with a concentration of 95% is introduced to activate for 24 hours, the space velocity of the activated gas is 40h ^-1 , and the difference between the concentration of the activated gas at the outlet and the initial concentration is stabilized within 1% within half an hour, and the activation is terminated;

(5) Feed in the raw materials HCl and acetylene, detect the change of the acetylene content at the outlet, and carry out normal production.

(6) Drive to test the regeneration effect, and determine the activation effect of each point.

Example 3

A method for regenerating a gold catalyst, comprising the following steps:

(1) Judging the degree of deactivation of the gold catalyst by the content of acetylene at the outlet;

(2) When the outlet acetylene content is 5%, any site is activated and regenerated;

(3) shut down the acetylene and hydrogen chloride gas, use _N to purge at the activation temperature, the activation temperature is 120°C, the purge time is 12h, and the space velocity of the inert gas is 39h ⁻¹ ;

(4) After the inert gas purging is completed, HCl with a concentration of 95% is introduced to activate for 24 hours, the space velocity of the activated gas is 40h ^-1 , and the difference between the concentration of the activated gas at the outlet and the initial concentration is stabilized within 1% within half an hour, and the activation is terminated;

(5) Feed in the raw materials HCl and acetylene, detect the change of the acetylene content at the outlet, and carry out normal production.

(6) Drive to test the regeneration effect, and determine the activation effect of each point.

Example 4

A method for regenerating a gold catalyst, comprising the following steps:

(1) Judging the degree of deactivation of the gold catalyst by the content of acetylene at the outlet;

(2) When the outlet acetylene content is 7%, any site is activated and regenerated;

(3) shut down the acetylene and hydrogen chloride gas, use _N to purge at the activation temperature, the activation temperature is 120°C, the purge time is 12h, and the space velocity of the inert gas is 30h ⁻¹ ;

(4) After the inert gas purging is completed, HCl with a concentration of 95% is introduced to activate for 24 hours, the space velocity of the activated gas is 40h ^-1 , and the difference between the concentration of the activated gas at the outlet and the initial concentration is stabilized within 1% within half an hour, and the activation is terminated;

(5) Feed in the raw materials HCl and acetylene, detect the change of the acetylene content at the outlet, and carry out normal production.

(6) Drive to test the regeneration effect, and determine the activation effect of each point.

Example 5

A method for regenerating a gold catalyst, comprising the following steps:

S1: Judging the degree of deactivation of the gold catalyst by the content of acetylene at the outlet;

S2: Activation and regeneration at any point when the outlet acetylene content is 7%;

S3: During the operation of the production device, HCl gas with a concentration of 95% is injected from the side line for activation, the HCl gas space velocity is 40h ^-1 , and the activation time is 24h;

S4: Stop HCl feeding, check the regeneration effect, and carry out normal production;

Comparative example 1:

A method for regenerating a gold catalyst, comprising the following steps:

S1: Judging the degree of deactivation of the gold catalyst by the content of acetylene at the outlet;

S2: Activation and regeneration at any point when the outlet acetylene content is 7%;

S3: Shut down and turn off the acetylene and hydrogen chloride gas, pass HCl with a concentration of 95% to activate for 24 hours, the space velocity of the activated gas is 40h ^-1 , the difference between the concentration of the activated gas at the outlet and the initial concentration is stabilized within 1% within half an hour, and the activation is terminated;

S5: Feed raw materials HCl and acetylene, detect changes in the content of acetylene at the outlet, and proceed with normal production.

S6: Drive to test the regeneration effect, and determine the activation effect of each point.

Comparative example 2:

A method for regenerating a gold catalyst, comprising the following steps:

S1: Judging the degree of deactivation of the gold catalyst by the content of acetylene at the outlet;

S2: when the outlet acetylene content is 7%, any site is activated and regenerated;

S3: shut down the acetylene and hydrogen chloride gas, use _N to purge at the activation temperature, the activation temperature is 120°C, the purge time is 12h, and the space velocity of the inert gas is 30h ⁻¹ ;

S4: After the inert gas purging is completed, pass air into it for activation for 24 hours, the space velocity of the activated gas is 40 h ^-1 , and the difference between the concentration of the activated gas at the outlet and the initial concentration is stabilized within 1% within half an hour, and the activation is terminated;

S5: Feed the raw material HCl and acetylene, detect the change of the acetylene content at the outlet, and carry out normal production.

S6: Drive to test the regeneration effect, and determine the activation effect of each point.

The specific regeneration results are shown in Table 1-2

Table 1

Table 2

It can be seen that, by selecting a specific regeneration reagent and regeneration temperature in the embodiment, the recovery rate of the initial conversion rate is greatly improved, and the catalytic activity of the catalyst is recovered to the greatest extent. Comparative example 1 and comparative example 2 show that not purging with inert gas before activation and activating with air have obvious influence on the regeneration result of the catalyst.

Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than limit the protection scope of the present invention. Simple modifications or equivalent replacements to the technical solution of the present invention by those skilled in the art will not depart from the present invention. The essence and scope of the technical solution of the invention.

Claims (10)

1. A method of regenerating a gold catalyst, characterized by: the method comprises the following steps:

(1) Judging the inactivation degree of the gold catalyst;

(2) Activating and regenerating at any site with the volume fraction of the acetylene content at the outlet of 2-25%;

(3) Purging with an inert gas at an activation temperature;

(4) After purging is finished, introducing activated gas for activation;

(5) After activation is finished, introducing HCl and acetylene;

(6) And (4) repeating the steps (1) to (4) when the content of the outlet acetylene is restored to the content before regeneration.

2. The regeneration method according to claim 1, characterized in that: the inert gas in the step (3) comprises nitrogen and/or argon.

3. The regeneration method according to claim 1, characterized in that: in the step (3), the activation temperature is 50-300 ℃, the purging time is 0-48h, and the space velocity of the inert gas is 10-50h ^-1 。

4. Regeneration method according to claim 1, characterized in that: the activating gas in the step (4) comprises Cl ₂ 、NO、N ₂ One or more of O and HCl.

5. A method for regenerating a gold catalyst, characterized by: the method comprises the following steps:

s1: judging the inactivation degree of the gold catalyst;

s2: activating and regenerating at any site with the content of acetylene at the outlet ranging from 2 to 25 percent;

s3: activating by introducing activating gas;

s4: stopping introducing the activated gas;

s5: when the outlet acetylene content is restored to the content before regeneration, steps S1 to S4 are repeated.

6. The regeneration method according to claim 5, characterized in that: the space velocity of the activated gas in the step S3 is 10-50h ^-1 The volume concentration is 95-100%.

7. The regeneration method according to claim 5, characterized in that: the activation time in the step S3 is 0-48h.

8. The regeneration method according to claim 5, characterized in that: and (3) introducing the activated gas from a pipeline during the operation of the production device.

9. The regeneration method according to claim 1 or 5, characterized in that: the position of the activation regeneration of the step (2) or S2 is a single site or more than one site.

10. Use of the regeneration process as claimed in claim 1 or 5 in a vinyl chloride production process.