CN108435193A - Reproducible removing organochlorine catalyst of one kind and preparation method thereof - Google Patents

Abstract

The invention discloses a renewable catalyst for removing organic chlorine and a preparation method thereof. The catalyst uses composite oxide synthesized from aluminum source, silicon source and magnesium source as carrier, and Ni, Mo, Cu and Ce as active components. According to the mass percentage of the catalyst, the NiO content in the active component is 6.2-15.6%, the CuO content is 16.1-25.4%, _the MoO content is 1.7-4.6%, _{the CeO} content is 1.5-2.5%, and the rest are carriers; The catalyst uses a composite oxide as a carrier, can better disperse active metals, has an ordered pore structure, a specific pore diameter, and a large pore volume. It can effectively remove organic chlorine, prevent subsequent devices from being corroded by inorganic chlorine, and improve the quality of oil products. At the same time, the catalyst can be continuously regenerated, reducing the start-up and shutdown time and reducing the production cost.

Description

A kind of renewable organic chlorine removal catalyst and preparation method thereof

technical field

The invention relates to a reproducible catalyst for removing organic chlorides in chlorinated naphtha and a preparation method thereof, belonging to the field of oil refining.

Background technique

In the late stage of oilfield exploitation, in order to increase the output of the oilfield, some additives containing organic chlorides will be used to increase the oil recovery rate, resulting in high chloride content in some crude oil, and the chlorine-containing compounds are mainly enriched in naphtha. Chlorides in naphtha are mainly chlorinated alkanes, such as chloroform, dichloromethane, trichloroethane, etc. The current crude oil desalting process can only remove the inorganic chlorides in the crude oil, but cannot remove the organic chlorides. Naphtha is used as a raw material for ethylene production and catalytic reforming. The organic chlorides in naphtha do not cause corrosion to equipment, but during the pre-hydrogenation process, organic chlorine undergoes a chemical reaction under the conditions of high temperature, high pressure and the presence of hydrogen to produce Hydrogen chloride will corrode the downstream equipment of the hydrogenation system. For example: Corrosion of the air-cooling equipment and water-cooling equipment of the pre-hydrogenation system; hydrogen chloride reacts with the ammonia produced by hydrogenation to form ammonium chloride, which blocks the pipeline; even enters the inlet of the pre-hydrogenation cycle hydrogen compressor, seriously affecting the normal operation of the cycle hydrogen compressor run. In order to prevent the corrosion of equipment caused by the conversion of organic chlorine into hydrogen chloride during crude oil processing, many researchers have developed various types of dechlorination agents, and some dechlorination agents have been used in industry for many years. However, these dechlorination agents mainly focus on the removal of inorganic chlorides in distillate oils, and there are few reports on dechlorination agents aimed at the removal of organic chlorine. US5928500 describes a method for removing trace organic chlorides in hydrocarbon components. The method uses silica with high porosity and high specific surface area as a carrier, and metals or metal oxides of Ni, Co or iron and their mixtures as active components Adsorbents that convert organic chlorides to metal chlorides to remove them. CN200810049261 patent describes an adsorbent for removing organic chlorides. This adsorbent uses porous materials such as molecular sieves, alumina, and activated carbon as a carrier, impregnated with metal chlorides or a mixture of metal chlorides and metal sulfates. The adsorbent can convert organic chlorides into inorganic chlorides under water-containing conditions, and then remove inorganic chlorides by washing with water, which will increase the dechlorination refining steps, resulting in cumbersome processes and further removal after washing. moisture problem. Although the impregnation method is simple to prepare, it will cause a sharp decrease in the surface area and pore volume of the adsorbent, thereby affecting the dynamic adsorption effect and bed life. US3864243 discloses a method for removing chlorides and other impurities in olefin components. Under room temperature and normal pressure conditions, 13X or 10X zeolite molecular sieves with a pore size of about 8A can be used to remove chlorides in hydrocarbon components by adsorption. The US20120190906 patent discloses the influence of the silicon-aluminum ratio of molecular sieves on the removal capacity of organochlorine, and the results show that 13X molecular sieves with a silicon-aluminum ratio lower than 1.25 have higher organochlorine adsorption capacity. Although 13X molecular sieve has a certain removal effect on organic chlorine, its total adsorption capacity is limited, its dynamic adsorption rate is low, and its service life is short.

Contents of the invention

The invention mainly aims at the shortcomings of the catalyst for removing organic chlorine in naphtha such as low chlorine capacity and non-renewability, and develops a regenerable catalyst for removing organic chlorides in oil products such as chlorinated naphtha . The invention provides a regenerable catalyst for removing organic chlorine and a preparation method thereof. The catalyst of the invention has good organic chlorine removal performance and can be regenerated and reused.

The catalyst of the invention uses the composite oxide synthesized from the aluminum source, the silicon source and the magnesium source as the carrier, and uses Ni, Mo, Cu and Ce as the active components to prepare a regenerable catalyst for removing organic chlorine.

The catalyst is characterized in that: the composite oxide synthesized by the aluminum source, the silicon source and the magnesium source has _a SiO content of 3% to 10% by mass percentage, a MgO content of 9.2 to 18.9%, and the rest are Al ₂ O ₃ .

The content of active components of the catalyst is based on the total mass of the catalyst, and the content of NiO in the active components is 6.2-15.6%, the content of CuO is 16.1-25.4%, the content of _MoO3 is 1.7-4.6%, and the content of _CeO2 is 1.5-2.5% %.

The catalyst is characterized in that the specific surface area of the catalyst is 430-526m ² /g, the pore volume is 0.85-1.1ml/g, and the pore diameter is 4-10nm.

The preparation method of the catalyst is characterized in that: a certain amount of aluminum source, silicon source, magnesium source, soluble nickel salt, surfactant and water are uniformly mixed to obtain the initial sol-gel mixture and moved into a synthesis kettle for sealing, Crystallize at 150~220°C for 8~24 hours. Adjust the pH value of the crystal slurry to neutral, add a certain amount of soluble molybdenum salt, soluble copper salt and soluble cerium salt into the reaction kettle, and carry out ion exchange reaction for 8~28h. After the reaction is completed, the above slurry is added to a flocculant for precipitation, filtered, washed, dried, extruded, and the filtered liquid is reused for the next reaction. After drying at 100-150°C for 2-4 hours and roasting at 500-700°C for 3-6 hours, a regenerable organic chlorine removal catalyst is obtained.

According to the catalyst provided by the present invention, the pore volume, specific surface area and pore diameter are measured by a nitrogen low temperature adsorption method.

The regenerable organochlorine removal catalyst prepared according to the method provided by the invention is suitable for treating distillate oil containing organochlorine, can effectively remove organochlorine, and produce distillate oil containing lower chlorine.

Compared with the prior art, the above-mentioned technical solution of the present invention has the following advantages:

(1) From the perspective of molecular structure design, the prepared catalyst has an ordered pore structure, specific pore diameter, and large pore volume. Utilizing the properties of the catalyst for adsorbing organic chlorine at low temperature and converting and desorbing organic chlorine at high temperature, it solves the drawbacks of previous catalysts that rely on simple adsorption to remove inorganic chlorine activity and cannot adsorb organic chlorine, and at the same time solves the problem that the chlorine capacity of organic chlorine adsorption catalysts is too low and cannot be regenerated .

(2) Magnesium silicate and aluminum silicate adsorbents have good adsorption capacity for organic chlorides in naphtha, and the two substances can be regarded as MgO·SiO ₂ , Al ₂ O ₃ ^.SiO ₂ , that is, the loading Silicon dioxide with metal oxides. In the mixed adsorbent, the two metal oxides of magnesium oxide and aluminum oxide have a synergistic effect, which increases the polarity of the adsorbent, thereby improving the adsorption capacity of the adsorbent for chlorides in naphtha.

(3) Ce facilitates better dispersion of active components such as Ni-Mo-Cu on the surface of the carrier, inhibits the growth of grains, increases the specific surface area and pore volume of the catalyst, and increases the chlorine capacity. During the catalyst roasting process, Ce ³⁺ is oxidized to Ce ⁴⁺ , and Ce ⁴⁺ has a stronger ability to obtain electrons, that is, the amount of L acid increases, and the total acid amount of the Ce modified catalyst increases, which can effectively inhibit oil Olefin polymerization, prevent coking of the catalyst, improve the anti-coking ability of the catalyst, and prolong the dechlorination life of the catalyst.

(4) The environment-friendly nickel-ammonia solution was used as a template, and the active component nickel was successfully embedded in the microporous catalyst precursor, which provided a basis for the subsequent synthesis of Ni-Mo-Cu-Ce as the active component catalyst. guarantee. Since the nickel is embedded in the micropores, it can better protect the nickel atoms when the temperature rises, and at the same time, the nickel activates the active chlorine adsorbed on the catalyst, and desorbs it from the catalyst through atom transfer; and ensures that the nickel on the catalyst Free from poisoning, renewable recycling.

Specific implementation examples:

The characteristics, preparation method and catalytic performance of the catalyst of the present invention will be described in detail below in conjunction with specific examples, but the present invention is not limited to these examples, nor does it constitute any limitation to the scope of the invention.

Example 1:

Mix 197g aluminum sol (Al ₂ O ₃ content 22%), 33.3g silica sol (SiO ₂ content 30%), 38.1g nickel nitrate, 2.5g tetraethylammonium bromide and 300g water, stir for 6h, mix well , to obtain an initial sol-gel mixture, and the initial sol-gel material was moved into a synthesis kettle and sealed, and crystallized at 220° C. for 8 hours. The pH value of the crystal slurry was adjusted to neutral with 0.5mol/L urea, and 4.28g ammonium molybdate, 59.7g copper nitrate and 6.3g cerium nitrate were added, and the ion exchange reaction was carried out for 8h. After the reaction is completed, the above slurry is added to a flocculant for precipitation, filtered, washed, dried, extruded, and the filtered liquid is reused for the next reaction. After drying at 150°C for 2 hours and calcining at 500°C for 6 hours, a regenerable adsorption dechlorination catalyst Cat1 was obtained.

Example 2:

179g of aluminum sol, 10g of silica sol, 44.6g of magnesium chloride, 15.1g of nickel nitrate, 2.5g of cetyltrimethylammonium bromide and 300g of water were stirred for 10 hours and mixed evenly to obtain the initial sol-gel mixture, and the initial sol-gel The glue material was moved into a synthesis kettle and sealed, and crystallized at 150 for 8 hours. The pH value of the crystal slurry was adjusted to neutral with 0.5mol/L urea, and 6.26g of ammonium molybdate, 59.7g of copper nitrate and 6.3g of cerium nitrate were added, and the ion exchange reaction was carried out for 28h. After the reaction is completed, the above slurry is added to a flocculant for precipitation, filtered, washed, dried, extruded, and the filtered liquid is reused for the next reaction. After drying at 120°C for 4 hours and calcining at 500°C for 6 hours, a regenerable adsorption dechlorination catalyst Cat2 was obtained.

Example 3

192.5g of aluminum sol, 23g of silica sol, 33g of magnesium chloride, 26.6g of nickel nitrate, 2.5g of tetraethylammonium bromide and 300g of water were stirred for 6 hours and mixed evenly to obtain the initial sol-gel mixture, and the initial sol-gel material was transferred to the synthetic The kettle was sealed and crystallized at 220°C for 20 hours. Use 0.5mol/L urea to adjust the pH value of the crystal slurry to neutral, add 4.28g ammonium molybdate, 48.7g copper nitrate and 5.1g cerium nitrate, and carry out ion exchange reaction for 20h. After the reaction is completed, the above slurry is added to a flocculant for precipitation, filtered, washed, dried, extruded, and the filtered liquid is reused for the next reaction. After drying at 120°C for 3 hours and calcining at 600°C for 5 hours, a regenerable adsorption dechlorination catalyst Cat3 was obtained.

Example 4:

244g of aluminum sol, 23g of silica sol, 21.7g of magnesium chloride, 26.6g of nickel nitrate, 2.5g of cetyltrimethylammonium bromide and 300g of water were stirred for 6 hours and mixed evenly to obtain the initial sol-gel mixture, and the initial sol-gel The rubber material was transferred into a synthesis kettle and sealed, and crystallized at 180° C. for 20 hours. Adjust the pH value of the crystal slurry to neutral with 0.5mol/L urea, add 2.3g ammonium molybdate, 37.8g copper nitrate and 3.78g cerium nitrate, and carry out ion exchange reaction for 28h. After the reaction is completed, the above slurry is added to a flocculant for precipitation, filtered, washed, dried, extruded, and the filtered liquid is reused for the next reaction. After drying at 100°C for 4 hours and calcining at 700°C for 3 hours, a regenerable adsorption dechlorination catalyst Cat4 was obtained.

Example 5:

In this embodiment, the activities of the dechlorination catalysts of the above-mentioned Examples 1-4 and the catalyst Cat5 of the prior art are compared and measured.

The pore properties and acid properties of the above products and coker gasoline desiliconization catalyst were analyzed, and the analysis results are shown in Table 1

Table 1 Physicochemical properties of different catalysts

It can be seen from Table 1 that MgO is introduced into the catalyst Cat2~4 carrier provided by the present invention, which has better specific surface area and pore volume than Cat1 without MgO. Catalysts Cat1-4 provided by the present invention have a larger pore diameter and pore volume than γ-Al ₂ O ₃ with the same composition through a specific preparation process.

Take 30ml of the catalysts prepared in each embodiment and put them into a reaction tube of Φ27×3.5mm, the height of the catalyst bed is 48mm, and the raw material oil used is naphtha. The properties are shown in Table 2.

Table 2 Properties of naphtha

project Density, g/ ^cm3 Total chlorine, μg/g naphtha 0.64 246

Selected analyzer: KY-200 microcoulomb chlorine content titrator to measure organic chlorine in oil. Take 30ml of catalyst and put it into a fixed bed reactor, activate the inside of the reactor, feed hydrogen, adjust the system pressure to 0.7MPa, the amount of hydrogen to 50mL/min, raise the temperature to 230°C at 10°C/min, keep the temperature for 2h, and then use the same The heating rate was raised to 400°C, and the temperature was kept constant for 4 hours to fully activate the catalyst. After the activation, the device was replaced with nitrogen, and the raw oil naphtha was pumped in. The oil inlet space velocity was 1.5h ^-1 , the reaction temperature was 150°C, the reaction pressure was 0.7MPa, and the nitrogen/oil ratio was 100:1 for dechlorination experiments. After dechlorination, the product is washed with water to remove inorganic chlorine, and then the organic chlorine content is analyzed. After the dechlorination effect of the catalyst decreases, the temperature of the catalyst is raised to 250°C at 10°C/min, the reaction pressure is increased to 1.4 MPa, and nitrogen is purged. When the chlorine content of the reactor outlet gas is detected to be zero, the regeneration is stopped. The reaction temperature was lowered to 150° C., the pressure was lowered to 0.7 MPa, and the dechlorination experiment was repeated. After reacting for a certain period of time, samples were taken and analyzed, and the reaction results were recorded as shown in Table 3.

Table 3 Dechlorination activity test results total chlorine, μg/g

From the data in Table 3, it can be known that Cat1, Cat2, Cat3, and Cat4 four kinds of dechlorination catalysts were used in the experiment of removing organic chlorine in naphtha organic chlorine content of about 240 μg/g raw material, and the removal of organic chlorine reached more than 97.9%, while the comparison Catalyst Cat5 is less effective in removing organochlorine in the presence of organochlorine. In order to further understand the performance of the catalyst of the present invention, the regeneration experiment of catalyst Cat 3 is carried out below, and the experimental results are shown in Table 3. The experimental results show that the Cat3 catalyst can effectively absorb and remove organic chlorine, and can be regenerated and reused. The inventor also used the above method to carry out long-term experiments on the catalysts obtained in other examples, all of which obtained good results, indicating that the catalyst of the present invention has good activity and stability.

Claims (9)

1. A renewable catalyst for removing organochlorine, characterized in that: the catalyst is based on a composite oxide synthesized from an aluminum source, a silicon source and a magnesium source, with Ni, Mo, Cu, and Ce as active components . 2. The catalyst according to claim 1, characterized in that: the composite oxide carrier has _{a SiO2} content of 3% to 10% by mass percentage, a MgO content of 9.2 to 18.9%, and the rest is _{Al2O 3} . 3. The catalyst according to claim 1, characterized in that: the aluminum source is aluminum sol; the silicon source is silica sol; the magnesium source is magnesium chloride. 4. The catalyst according to claim 1, characterized in that: the specific surface area of the catalyst is 430-526m ² /g, the pore volume is 0.85-1.1ml/g, and the pore diameter is 4-10nm. 5. according to the described catalyst of claim 1, it is characterized in that: catalyst active component content is based on catalyst gross mass, and in its active component, NiO content is 6.2-15.6%, CuO content is 16.1-25.4%, MoO _Content 1.7-4.6%, CeO ₂ content is 1.5-2.5%. 6. according to the preparation method of the described catalyst of any one of claim 1～5, it is characterized in that: a kind of preparation method of regenerable removal organochlorine catalyst is as follows: Mix a certain amount of aluminum source, silicon source, magnesium source, soluble nickel salt, surfactant and water evenly to obtain the initial sol-gel mixture, move it into a synthesis kettle and seal it, and crystallize at 150~220°C for 8~24 hours; Adjust the pH value of the crystal slurry to neutral, add a certain amount of soluble molybdenum salt, soluble copper salt and soluble cerium salt to the reaction kettle, and carry out ion exchange reaction for 8~28h; after the reaction is completed, add the above slurry The flocculant is precipitated, filtered, washed, dried, extruded, and the filtered liquid is reused for the next reaction; dried at 100-150°C for 2-4 hours, and roasted at 500-700°C for 3-6 hours to obtain a Regenerated organochlorine removal catalyst. 7. The preparation method of catalyst according to claim 6, characterized in that: the surfactant is tetraethylammonium bromide or cetyltrimethylammonium bromide. 8. The preparation method of the catalyst according to claim 6, characterized in that: the pH value of the crystal slurry is adjusted to neutrality with urea. 9. The preparation method of the catalyst according to claim 6, characterized in that: the soluble molybdenum salt, copper salt and cerium salt are ammonium salts or nitrates.