CN112725022B

CN112725022B - Hydrodewaxing method

Info

Publication number: CN112725022B
Application number: CN201911031521.2A
Authority: CN
Inventors: 郝文月; 刘昶; 郭俊辉; 王凤来; 曹均丰; 黄薇; 廖杰峰
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2019-10-28
Filing date: 2019-10-28
Publication date: 2023-01-10
Anticipated expiration: 2039-10-28
Also published as: CN112725022A

Abstract

The invention discloses a hydrodewaxing method, raw waxy diesel oil passes through a hydrofining reaction zone and a hydrodewaxing reaction zone which are alternately connected in series and then is separated to obtain a low-freezing-point diesel oil product, wherein the hydrodewaxing reaction zone is filled with a dewaxing catalyst containing a ZSM-5 molecular sieve, and the cracking rate of the dewaxing catalyst to 1,3, 5-triisopropylbenzene is less than 2%. The method can obviously improve the yield of the low-freezing-point diesel.

Description

Hydrodewaxing method

Technical Field

The invention relates to a hydrodewaxing method, in particular to a hydrodewaxing method for improving the cracking selectivity of normal paraffin and increasing the yield of diesel oil.

Background

The China is very long in the three northeast, northwest and west regions and the Tibet, etc. in winter, the demand for the diesel oil with good low-temperature fluidity is more vigorous in cold seasons, and the low-freezing point diesel oil (-20) is produced ^# 、-35 ^# ) The efficiency of the method is remarkable, oil refining enterprises hope to increase the yield of low-freezing diesel oil products, and the economic efficiency of the enterprises is further increased. The diesel oil yield is strictly limited by the condensation point of distillate oil, and the contradiction between the diesel oil yield and the low-temperature fluidity of the diesel oil is more prominent in northern cold regions, so that the method becomes a key problem for limiting the economic benefit of northern oil refining enterprises.

In view of the reason that long-chain normal paraffin and aromatic hydrocarbon cause poor low-temperature fluidity of oil products, the improvement of the low-temperature fluidity of the oil products requires hydrogenation to destroy the structures of benzene rings and cyclane, and the oil products have cracking and isomerization performance of the long-chain paraffin, because the content of the aromatic hydrocarbon and the cyclane in diesel oil and jet fuel is not high, the over-cracking can cause the component of the oil products to be transferred to light components, and the conversion of the long-chain paraffin into the isoparaffin with better low-temperature fluidity through isomerization becomes the key for improving the low-temperature fluidity of the oil products.

At present, the hydrodewaxing catalyst used usually adopts a shape-selective molecular sieve and an alumina binder as carriers, and a small amount (no more than 5% of the weight of the catalyst) of metal with dehydrogenation activity is added. Wherein ZSM-5 molecular sieve is generally adopted as the shape-selective molecular sieve. The size of the straight cylindrical pore canal of the ZSM-5 molecular sieve is 0.51 nm multiplied by 0.56nm, and the size of the zigzag pore canal is 0.54nm multiplied by 0.56nm.

CN85100324A discloses a distillate oil hydrodewaxing catalyst and a preparation method thereof, and the catalyst is prepared by using ZSM-5 zeolite molecular sieve directly synthesized by an amine-free method as a matrix, performing acid treatment, adding an adhesive, kneading and forming, adding an active metal component, and performing steam heat treatment. Wherein the binder is preferably small-pore alumina, the active metal component is preferably nickel, and the addition method can be impregnation, kneading and ion exchange. CN101143333A proposes a preparation method of a hydrodewaxing catalyst with certain hydrorefining function. The method makes full use of the binder component in the hydrodewaxing catalyst and takes the binder component as a carrier of the catalyst with hydrofining performance, thereby obviously improving the hydrofining performance of the catalyst. CN201010514426.0 proposes that a nano ZSM-5 molecular sieve, macroporous alumina and a binder are kneaded to form a carrier, then the carrier is impregnated with a supported active metal, and finally the catalyst is obtained through hydrothermal treatment. CN201010514141.7 discloses a diesel hydrodewaxing method. The method comprises the following steps: the wax-containing diesel raw material sequentially passes through a hydrodewaxing catalyst bed layer and a hydrofining catalyst bed layer which are alternately and serially filled, and finally the obtained hydrofining product is separated to obtain a diesel product.

The above patent improves the yield and quality of the hydrodewaxing unit by improving the catalyst or adjusting the process, but the yield of the diesel still needs to be further improved.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a hydrodewaxing method which can obviously improve the yield of low-freezing-point diesel.

A hydrodewaxing method for preparing diesel oil containing wax includes such steps as passing the raw diesel oil through the hydrorefining reaction region and hydrodewaxing reaction region which are alternatively connected in series, separating to obtain low-freezing-point diesel oil, loading the hydrodewaxing reaction region with the dewaxing catalyst containing ZSM-5 molecular sieve, and catalytic dewaxingThe cracking rate of the agent to 1,3, 5-triisopropylbenzene is less than 2%, preferably less than 1.5%, more preferably less than 1%, and specifically may be 0.5%, 0.8%, 0.4%, the cracking conditions are that the flow rate of inert gas is 100mL/min, and the hourly space velocity of 1,3, 5-triisopropylbenzene liquid is 1.0h ^-1 The reaction temperature is 350 ℃ and the normal pressure is high.

In the above method, the number of the hydrofining reaction zones is at least 1, preferably 2; the hydrodewaxing reaction zone is at least set to be 1, preferably 2, the number of the hydrofining reaction zone and the hydrodewaxing reaction zone can be the same or different, and the hydrofining reaction zone and the hydrodewaxing reaction zone are within the protection range of the application as long as the requirement of alternative setting is met, but the number of the hydrofining reaction zone and the hydrodewaxing reaction zone is preferably set to be the same.

In the method, the mass content of the wax in the wax-containing diesel raw material is 20 to 40 wt%, preferably 30 to 40 wt%, relative to the total weight of the wax-containing diesel, and the wax is n-alkane containing 10 to 25 carbons.

In the method, the properties of the catalyst filled in the hydrofining reaction zone are as follows: generally, metals in a VIB group and/or a VIII group are used as active components, alumina or silicon-containing alumina is used as a carrier, the metals in the VIB group are generally Mo and/or W, and the metals in the VIII group are generally Co and/or Ni. Based on the weight of the catalyst, the content of the VIB group metal is 8-28 wt percent calculated by oxide, the content of the VIII group metal is 2-15 wt percent calculated by oxide, and the properties are as follows: the specific surface area is 100 to 650m ² (ii)/g, pore volume of 0.15-0.8 mL/g, and a wide variety of commercial catalysts can be selected, such as hydrofining catalysts developed by the research and development of petrochemical research institute (FRIPP), FF series, FH-UDS series, and the like; conventional hydrotreating oxidation state catalysts may also be prepared as desired according to common general knowledge in the art.

In the above method, the operating conditions of the hydrorefining reaction zone are as follows: the reaction pressure is 6.0-20.0 MPa, the volume ratio of hydrogen to oil is 200-1500, and the volume airspeed is 0.1-10.0 h ^-1 The reaction temperature is 270-460 ℃; the preferable operation conditions are that the reaction pressure is 7.0-15.0 MPa, the volume ratio of hydrogen to oil is 300-1, and the volume space velocity is 0.3-8.0 h ^-1 The reaction temperature is 315-415 DEG C。

In the method, the hydrodewaxing catalyst filled in the hydrodewaxing reaction zone takes a ZSM-5 molecular sieve as an acidic component and takes VIB group and/or VIII group metals as hydrogenation active metal components. The ZSM-5 molecular sieve has a silica-alumina molar ratio of 10-150, preferably 20-120. The VIB group metal is one or more of Mo and W, and the VIII group metal is one or more of Co and Ni. Based on the weight of the hydrodewaxing catalyst, the weight content of the hydrogenation active metal component is 1-16 percent calculated by oxide, and the weight content of the ZSM-5 molecular sieve is 50-85 percent.

In the above method, the hydrodewaxing reaction zone has the following operating conditions: the reaction pressure is 6.0-20.0 MPa, the volume ratio of hydrogen to oil is 200-1500, and the volume airspeed is 0.1-10.0 h ^-1 The reaction temperature is 260-455 ℃; the preferable operating conditions are that the reaction pressure is 7.0-15.0 MPa, the volume ratio of hydrogen to oil is 300 ^-1 The reaction temperature is 310-410 ℃.

In the method, the pour point depressing catalyst is prepared by treating the outer surface to reduce or remove the acid sites on the outer surface of the pour point depressing catalyst. For example, the high-temperature heat treatment is carried out on the pour point depressing catalyst commodity or the self-made pour point depressing catalyst by adopting macromolecular organic matters which at least can not enter the inside of the pour point depressing catalyst pore canal. The treatment can be carried out outside the reactor or inside the reactor after the catalyst is filled.

The pretreatment method adopted in the embodiment of the invention is as follows: putting a commercial grade or self-made pour point depression catalyst into a fixed bed reactor, taking 1,3, 5-triisopropylbenzene as a raw material, and controlling the volume flow of nitrogen at 50-100 mL/min, the reaction temperature at 380-460 ℃, and the volume airspeed of 1,3, 5-triisopropylbenzene liquid at 0.5-1.0 h ^-1 Processing for 4 to 12 hours under the condition of (1) to obtain the final catalyst. Research results show that the process can be completely carried out on a hydrodewaxing device, even if 1,3, 5-triisopropylbenzene passes through a hydrofining reaction zone, the hydrofining reaction zone is not affected adversely, and pre-vulcanization and normal operation processes are carried out after treatment is finished.

Compared with the prior art, the hydrodewaxing method of the invention can obviously reduce side reactions and improve the yield of low-pour diesel oil.

Detailed Description

The following examples and comparative examples are given to further illustrate the effects and effects of the method of the present invention, but the following examples are not intended to limit the method of the present invention, and all% referred to in the present application are mass percentages unless otherwise specified.

The refined catalysts used in the examples and comparative examples of the present application had the following composition using alumina or silica-containing alumina as a carrier and Mo and Co as cracking components. Based on the weight of the catalyst, the Mo content is 15wt% calculated by oxide, the Co content is 5wt% calculated by oxide, and the operating conditions of the refining reaction zone are as follows: the reaction pressure is 7.0MPa, the volume ratio of hydrogen to oil is 500, and the volume space velocity is 1.0h ^-1 The reaction temperature is 340 ℃; the pour point depressant catalyst before pretreatment consists of: ZSM-5 molecular sieve is used as an acidic component with the content of 10 wt%, ni is used as a hydrogenation active metal component with the content of 7 wt% calculated by oxide, and the balance is alumina and a binder; the hydrodewaxing reaction zone operating conditions are as follows: the reaction pressure is 7.0MPa, the volume ratio of hydrogen to oil is 500, and the volume space velocity is 2.0 h ^-1 The reaction temperature is 350 ℃; the properties of the waxy diesel feedstock are shown in table 1.

TABLE 1 Properties of the stock oils

Comparative example 1

The packed hydrodewaxing catalyst is not pretreated, and the volume space velocity is 1.0h when the flow rate of inert gas is 100mL/min and the liquid of 1,3, 5-triisopropylbenzene is ^-1 The cracking rate of 1,3, 5-triisopropylbenzene measured at 350 ℃ under normal pressure is 20.4 wt%. The distribution and properties of the hydrodewaxing products obtained from the raw materials shown in Table 1 are shown in Table 2.

Table 2 comparative example 1 product distribution and properties

Example 1

The packed hydrodewaxing catalyst is treated as follows: the volume space velocity of 1,3, 5-triisopropylbenzene liquid is 0.5h when the volume flow of nitrogen is 50 mL/min, the reaction temperature is 380 DEG and the volume space velocity of 1,3, 5-triisopropylbenzene liquid is 0.5h ^-1 For 4 hours under the condition of (1); the flow rate of inert gas is 100mL/min, and the hourly space velocity of 1,3, 5-triisopropylbenzene liquid is 1.0h ^-1 The cracking rate of 1,3, 5-triisopropylbenzene measured at 350 ℃ under normal pressure is 1.8 wt%. The distribution and properties of the hydrodewaxing products obtained using the raw materials as shown in Table 1 are shown in Table 3.

Table 3 example 1 product distribution and properties

Example 2

The packed hydrodewaxing catalyst is treated as follows: the volume space velocity of 1,3, 5-triisopropylbenzene liquid is 0.5h at the conditions that the volume flow of nitrogen is 50 mL/min, the reaction temperature is 400 ℃ and the volume space velocity of 1,3, 5-triisopropylbenzene liquid is 0.5h ^-1 For 6 hours under the conditions of (1); the flow rate of inert gas is 100mL/min, and the hourly space velocity of 1,3, 5-triisopropylbenzene liquid is 1.0h ^-1 The cracking rate of the 1,3, 5-triisopropylbenzene is 1.2 wt% measured at 350 ℃ and normal pressure. The distribution and properties of the hydrodewaxing products obtained using the raw materials as shown in Table 1 are shown in Table 4.

Table 4 example 2 product distribution and properties

Example 3

The packed hydrodewaxing catalyst is treated by: the volume flow rate of nitrogen is 100mL/min, the reaction temperature is 400 ℃, and the hourly volume space velocity of 1,3, 5-triisopropylbenzene liquid is 1.0h ^-1 For 6 hours under the conditions of (1); the volume space velocity at the time of 1,3, 5-triisopropylbenzene liquid with the flow rate of inert gas of 100mL/min1.0h ^-1 The cracking rate of the 1,3, 5-triisopropylbenzene is 1.0 wt% measured at 350 ℃ and normal pressure. The distribution and properties of the hydrodewaxing products obtained using the raw materials as shown in Table 1 are shown in Table 5.

Table 5 example 3 product distribution and properties

Product(s)	Naphtha (a)	Diesel oil
			Yield wt%	13.4	81.3
Freezing point of	--	-22

Example 4

The packed hydrodewaxing catalyst is treated as follows: the volume space velocity of 1,3, 5-triisopropylbenzene liquid is 1.0h when the volume flow of nitrogen is 100mL/min, the reaction temperature is 420 ℃ and the volume space velocity of 1,3, 5-triisopropylbenzene liquid is ^-1 For 8 hours under the conditions of (1); the volume space velocity at the time of 1,3, 5-triisopropylbenzene liquid is 1.0h under the condition that the flow rate of inert gas is 100mL/min ^-1 The cracking rate of the 1,3, 5-triisopropylbenzene is 0.8 wt% measured at 350 ℃ and normal pressure. The distribution and properties of the hydrodewaxing products obtained using the raw materials as shown in Table 1 are shown in Table 6.

Table 6 example 4 product distribution and properties

Product(s)	Naphtha (a)	Diesel oil
			Yield wt%	12.3	82.7
Freezing point of	--	-23

Example 5

The packed hydrodewaxing catalyst is treated by: the volume space velocity of 1,3, 5-triisopropylbenzene liquid is 1.0h when the volume flow of nitrogen is 100mL/min, the reaction temperature is 420 ℃ and the volume space velocity of 1,3, 5-triisopropylbenzene liquid is ^-1 For 12 hours under the condition of (1); the volume space velocity at the time of 1,3, 5-triisopropylbenzene liquid is 1.0h under the condition that the flow rate of inert gas is 100mL/min ^-1 The cracking rate of the 1,3, 5-triisopropylbenzene is 0.5 wt% measured at 350 ℃ and normal pressure. The distribution and properties of the hydrodewaxing products obtained using the raw materials as shown in Table 1 are shown in Table 7.

Table 7 example 5 product distribution and properties

Product(s)	Naphtha (a)	Diesel oil
			Yield wt%	11.5	83.8
Freezing point of	--	-23

Example 6

The packed hydrodewaxing catalyst is treated by: the volume space velocity of 1,3, 5-triisopropylbenzene liquid is 1.0h when the volume flow of nitrogen is 100mL/min, the reaction temperature is 440 DEG and the volume space velocity of 1,3, 5-triisopropylbenzene liquid is ^-1 For 8 hours under the conditions of (1); the flow rate of inert gas is 100mL/min, and the hourly space velocity of 1,3, 5-triisopropylbenzene liquid is 1.0h ^-1 The cracking rate of 1,3, 5-triisopropylbenzene measured at 350 ℃ under normal pressure was 0.4 wt%. The distribution and properties of the hydrodewaxing products obtained using the raw materials as shown in Table 1 are shown in Table 8.

Table 8 example 6 product distribution and properties

Product(s)	Naphtha fraction	Diesel oil
			Yield wt%	10.7	84.5
Freezing point of	--	-20

Example 7

The packed hydrodewaxing catalyst is treated by: the volume space velocity of 1,3, 5-triisopropylbenzene liquid is 1.0h when the volume flow of nitrogen is 100mL/min, the reaction temperature is 460 ℃ and the volume space velocity of 1,3, 5-triisopropylbenzene liquid is ^-1 For 12 hours under the condition of (1); the flow rate of inert gas is 100mL/min, and the hourly space velocity of 1,3, 5-triisopropylbenzene liquid is 1.0h ^-1 The cracking rate of 1,3, 5-triisopropylbenzene measured at 350 ℃ under normal pressure is 0.2 wt%. The distribution and properties of the hydrodewaxing products obtained using the raw materials as shown in Table 1 are shown in Table 9.

Table 9 example 7 product distribution and properties

Product(s)	Naphtha (a)	Diesel oil
			Yield wt%	10.0	84.6
Freezing point of	--	-18

Claims

1. A hydrodewaxing method is characterized in that: the wax-containing diesel raw oil passes through a hydrofining reaction zone and a hydrodewaxing reaction zone which are alternately connected in series and then is separated to obtain a low pour point diesel product, wherein the hydrodewaxing reaction zone is filled with a mixture containingThe pour point depressing catalyst is a pour point depressing catalyst of a ZSM-5 molecular sieve, the cracking rate of the pour point depressing catalyst to 1,3, 5-triisopropylbenzene is less than 2 percent, and the pour point depressing catalyst is prepared by treating the outer surface to reduce or remove the acid sites on the outer surface of the pour point depressing catalyst; the treatment is to place commercial grade or self-made pour point depression catalyst in a fixed bed reactor, take 1,3, 5-triisopropylbenzene as raw material, and the volume airspeed of 1,3, 5-triisopropylbenzene liquid is 0.5-1.0 h at the reaction temperature of 380-460 ℃ and the volume flow of nitrogen of 50-100 mL/min ^-1 Treating for 4-12 h under the condition of (1) to obtain the pour point depressing catalyst.

2. The method of claim 1, wherein: the pour point depressing catalyst has a cracking rate of less than 1.5% to 1,3, 5-triisopropylbenzene.

3. The method of claim 1, wherein: the number of the hydrofining reaction zones is at least 1; the number of the hydrodewaxing reaction zone is at least 1, and the number of the hydrofining reaction zone is the same as or different from that of the hydrodewaxing reaction zone.

4. The method of claim 1, wherein: the mass content of the wax in the raw material of the wax-containing diesel oil is 20-40 wt% relative to the total weight of the wax-containing diesel oil.

5. The method of claim 1, wherein: the properties of the catalyst filled in the hydrofining reaction zone are as follows: the VIB group and/or VIII group metal is used as an active component, and alumina or silicon-containing alumina is used as a carrier.

6. The method of claim 5, wherein: the VIB group metal is Mo and/or W, the VIII group metal is Co and/or Ni, and the VIB group metal content is 8-28 wt% by oxide and the VIII group metal content is 2-15 wt% by oxide based on the weight of the refined catalyst.

7. The method of claim 1, wherein: the operating conditions of the hydrofining reaction zone are as follows: the reaction pressure is 6.0-20.0 MPa, the volume ratio of hydrogen to oil is 200-1500, and the volume airspeed is 0.1-10.0 h ^-1 The reaction temperature is 270-460 ℃.

8. The method of claim 7, wherein: the operating conditions of the hydrofining reaction zone are as follows: the reaction pressure is 7.0-15.0 MPa, the volume ratio of hydrogen to oil is 300 ^-1 The reaction temperature is 315-415 ℃.

9. The method of claim 1, wherein: the hydrodewaxing catalyst filled in the hydrodewaxing reaction zone takes a ZSM-5 molecular sieve as an acidic component and a VIB group and/or VIII group metal as a hydrogenation active metal component.

10. The method of claim 9, wherein: the silicon-aluminum molar ratio of the ZSM-5 molecular sieve is 10-150, the VIB group metal is one or more of Mo and W, and the VIII group metal is one or more of Co and Ni; based on the weight of the hydrodewaxing catalyst, the weight content of the hydrogenation active metal component is 1-16% in terms of oxide, and the weight content of the ZSM-5 molecular sieve is 50-85%.

11. The method of claim 1, wherein: the operating conditions of the hydrodewaxing reaction zone are as follows: the reaction pressure is 6.0-20.0 MPa, the volume ratio of hydrogen to oil is 200-1500, and the volume airspeed is 0.1-10.0 h ^-1 The reaction temperature is 260-455 ℃.

12. The method of claim 11, wherein: the operating conditions of the hydrodewaxing reaction zone are as follows: the reaction pressure is 7.0-15.0 MPa, the volume ratio of hydrogen to oil is 300 ^-1 The reaction temperature is 310-410 ℃.