CN101157051A - Recovery Method of Microsphere Catalyst Used in Fluidized Bed - Google Patents

Abstract

A method for recovering microsphere catalysts used in a fluidized bed is to mix the catalyst to be recovered with the raw materials for preparing fresh microsphere catalysts in a certain proportion, spray dry the slurry after colloidal grinding, and roast at high temperature to obtain a microsphere catalyst with low wear and tear. A microsphere catalyst with an index and a suitable particle size distribution; its preparation process is as follows: 1) According to a certain oxide dry basis ratio, the catalyst to be recovered is mixed with the original powder of molecular sieve, binder, auxiliary agent, pore-forming agent and deionized Mixing with water, beating, and the weight content of the oxide dry basis of the recovered catalyst in the total batching is not more than 80%; 2) The slurry is passed through a colloid mill, so that the diameter of the solid particles contained therein is less than 20 μm, and 90% of the The particle diameter is less than 10 μm, and 70% of the particle diameter is less than 5 μm; 3) Spray drying to obtain a microsphere sample; 4) Roasting the microsphere sample in an oxygen-containing atmosphere at 500-800° C. to obtain a microsphere catalyst for a fluidized bed. The recovered and prepared microsphere catalyst can be used in the reaction of converting oxygen-containing compounds into olefins.

Description

Recovery Method of Microsphere Catalyst Used in Fluidized Bed

technical field

The invention relates to a method for recovering a microsphere catalyst used in a fluidized bed and the catalytic application of the recovered catalyst in the reaction of converting oxygen-containing compounds into olefins.

Background technique

Ethylene and propylene are important basic chemical raw materials. At present, my country mainly adopts light oil cracking method to prepare them. With the shortage of petroleum resources and rising prices, the technology of producing low-carbon olefins through non-petroleum routes is becoming increasingly urgent. The research and development of ethylene and propylene has become a hot spot for domestic and foreign research institutions and major international companies to invest in technology. The single-series and large-scale industrialization technology for producing methanol from natural gas or coal is very mature, so the research on producing olefins (MTO) from methanol has become a key technology for producing low-carbon olefins through non-petroleum routes.

Small-pore phosphorus-silicate-aluminum molecular sieves have good MTO catalytic performance, but have the characteristics of rapid carbon deposition in the fixed-bed reaction process, resulting in rapid deactivation and selectivity reduction of the catalyst, which cannot meet the requirements of industrial continuous production. The fluidized bed is a common reactor form used in the chemical industry. The MTO process of the fluidized bed reactor with continuous reaction-regeneration can avoid the above problems. Catalysts suitable for fluidized bed reactors should be in the form of microspheres with suitable strength and particle size distribution under the premise of maintaining high catalytic performance.

At present, microsphere catalysts for fluidized beds are prepared by spray drying. Generally speaking, microsphere catalysts are composed of active components such as molecular sieves and binders, and the binder plays the role of dispersing the active components and improving the strength of the catalyst. In addition, the presence of inactive components in the catalyst can also dilute the molecular sieve, thereby reducing the heat effect of reaction. Such as USP5126298 has reported the preparation of a kind of high-strength cracking catalyst, two kinds of different clays, zeolite molecular sieve and phosphorus-containing compound are made the slurry of pH＜3, and spray drying makes; USP5248647 has reported SAPO-34 molecular sieve, kaolin A slurry spray-drying method made with silica sol; USP6153552 reports a method for preparing a microsphere catalyst containing SAPO molecular sieve, which is prepared by mixing SAPO molecular sieve, inorganic oxide sol, and phosphorus-containing compound, and spray-drying; USP6787501 has reported that SAPO-34 molecular sieve, binding agent and matrix material are made into catalyst for methanol conversion through spray drying; CN01132533A has reported the preparation of wear resistance index catalyst for methanol conversion, which is by reducing the mass content of molecular sieve in the catalyst It has the effect of improving the catalyst wear index.

When the catalyst is produced by the spray drying method, two products with different particle size distributions, coarse powder and fine powder, will be obtained at the same time. The particle size distribution of the catalyst actually used in the fluidized bed has certain requirements, and it is generally prepared by mixing coarse powder and fine powder in proportion. If the preparation ratio of the catalyst is different from the ratio of coarse powder and fine powder in the production process, there will be a part of the catalyst remaining. If the remaining catalyst is not recycled, it will not only cause loss of production, but also increase production cost. In addition, the catalyst will be attrition in the circulating fluidized bed unit, and most of the pulverized catalyst can be recovered by cyclone separation equipment. If these pulverized catalysts still maintain the original excellent reaction performance, their recycling will also reduce the production cost of the catalyst, which has certain economic value.

Patent CN1516177A reports a method of reusing molecular sieve-containing catalysts, that is, mixing molecular sieve-containing microsphere catalysts with a large amount of deionized water, rubber milling to reduce the particle size of the particles in the slurry, and then re-spray-drying to prepare a catalyst with a lower wear index. and catalysts with suitable particle size distribution. However, it should be pointed out that the catalyst used for recovery must be a fresh unroasted sample, that is, the molecular sieve contains an organic template. The method of recovering and reusing the catalyst after reaction (carbon-containing sample or sample after roasting) to prepare microsphere catalyst for fluidized bed has not been reported in the literature so far.

Contents of the invention

The inventors' research work has shown that any catalyst that cannot be directly used in a fluidized bed reactor (wear index and morphology cannot meet the requirements), that is, fresh uncalcined catalyst, freshly calcined catalyst, reacted carbon-containing catalyst and reacted Afterwards, the carbon-removed catalyst is calcined and reused to prepare a microsphere catalyst for a fluidized bed with a lower wear index and a suitable wear index. Please refer to our patent application (Application No. 200610089171.1) for the detailed preparation method of the fresh microsphere catalyst used in the conversion of oxygenates to olefins referred to in this patent.

One of the purposes of the present invention is to provide a method for recovering the microsphere catalyst used in a fluidized bed. In the method, the catalyst to be recovered is mixed with raw materials for preparing fresh microsphere catalysts in a certain proportion, the slurry is rubber-milled, spray-dried and calcined at a high temperature, and a microsphere catalyst with a lower wear index and suitable particle size distribution can be obtained.

The above-mentioned recovery method of the present invention is characterized in that the microsphere catalyst referred to is prepared by SAPO/MeAPSO molecular sieve as an active component, adding a binder, an auxiliary agent and a pore-forming agent. The element composition (mass content) in the catalyst is 2-60% of silicon oxide, 8-50% of phosphorus oxide, 20-70% of aluminum oxide, 0-10% of alkaline earth metal oxide, 0-20% of transition metal oxide, and satisfy The sum of the total mass content is 100%. Among them, the SAPO/MeAPSO molecular sieve referred to is its original powder form, that is, the molecular sieve contains organic templates introduced during the synthesis process, and the pore size is less than 0.5nm; the metals contained in the MeAPSO molecular sieve are titanium, vanadium, chromium, manganese, iron, One or any mixture of cobalt, nickel, copper, zinc, zirconium, etc.; the binder is one or a mixture of kaolin, bentonite, montmorillonite, aluminum sol, silica sol, and alumina The auxiliary agent is one or a mixture of calcium, strontium, barium and zirconium oxides, inorganic salts or organic salts; the auxiliary agent referred to can also be phosphoric acid, diammonium hydrogen phosphate, ammonium hydrogen phosphate One or a mixture of several of them; the pore-forming agent is an organic compound, preferably a natural product such as kale powder.

The feature of the present invention is that the catalyst to be recovered can be fresh microsphere catalyst (roasting or unroasted sample), also can be the catalyst after reaction (carbon-containing or roasting carbon removal sample), can also be cyclone separation by fluidized bed The device recovers the obtained catalyst powder (carbon-containing or roasted to remove carbon samples). Among them, the content of molecular sieve in the catalyst obtained by cyclone separation is similar to that of the fresh catalyst.

Specifically, the preparation process of the microsphere catalyst recovery method of the present invention as active component by molecular sieve is as follows:

1) Mix the catalyst to be recovered with the original molecular sieve powder, binder, auxiliary agent, pore-forming agent and deionized water according to a certain oxide dry basis ratio, and beat;

2) The slurry is passed through a colloid mill, so that the diameter of the solid particles contained therein is less than 20 μm, 90% of the particle diameter is less than 10 μm, and 70% of the particle diameter is less than 5 μm;

3) Spray drying with a pressure spray drying device or a centrifugal spray drying device to prepare microsphere samples. The particle size distribution of the catalyst microsphere particles can be modulated by the pressure change (0.5-2.5MPa) of the nozzle in the pressure spray drying equipment or the change of the rotational speed (25-40Hz) of the atomizer in the centrifugal spray drying equipment. The inlet temperature of the spray drying equipment is 300-500°C, and the outlet temperature is not lower than 100°C.

4) Calcining the microsphere sample in an oxygen-containing atmosphere at 500-800° C. to obtain a microsphere catalyst for a fluidized bed.

Wherein, the dry basis content of the oxides in the total batching of the recovered catalyst is no more than 80%, the preferred range is 10-80%; the recovered catalyst and molecular sieve powder are SAPO/MeAPSO molecular sieves and the oxides in the total batching The dry basis content is 20-50%; the oxide dry basis content of the binder in the total ingredients is 10-75%; the oxide dry basis content of the auxiliary agent in the total ingredients is 0-30%; The content in the total batching is 0-2%.

The present invention is characterized in that the wear index of the microsphere catalyst is less than 2.

Another object of the present invention is to directly apply the microsphere catalyst prepared above to a circulating fluidized bed for the conversion of oxygenates to olefins, as a catalyst with suitable particle size distribution, attrition index and high catalytic activity.

Detailed ways

The present invention is described in detail below by way of examples.

Example 1

It is 30wt% to calculate by oxide dry base solid content in feed liquid, the silica sol (content 30wt%) of metering, aluminum sol (content 20%), calcium nitrate (content 23%), kaolin (content 85wt%) and SAPO The former powder of -34 molecular sieve was added into a certain amount of deionized water in sequence, and stirred for 30 minutes (the oxide dry basis mass content of each raw material was respectively 25%, 10%, 5%, 30%, and 30%) in sequence, and finally added Squash powder (soaked with a small amount of ethanol) equivalent to 0.5% of the dry weight of the total oxides, stirred for 30 minutes. The feed liquid is passed through a colloid mill for colloid milling, so that 70% of the particle diameters in the finally obtained slurry are less than 5 μm. After the slurry was left at room temperature for 2 hours, it was subjected to centrifugal spray drying, the atomizer rotated at 30 Hz, the inlet temperature was 400°C, and the outlet temperature was not lower than 120°C. The obtained spray-dried product is denoted as M, and the product is calcined in the air at 650°C for 4 hours to obtain the catalyst for the conversion of oxygenates to olefins, denoted as MC.

Example 2

The MC sample obtained in Example 1 was used in a circulating fluidized bed (catalyst loading capacity of 4 tons, methanol processing capacity of 50 tons/day) in an industrial test to carry out methanol conversion to olefins reaction. After 30 days of stable operation of the device, the collected catalyst powder was taken out from the sampling port of the cyclone separator, and recorded as XM. A small amount of catalyst sample was taken from the sampling port of the reactor, denoted as FM.

Example 3

Some samples of XM and FM were taken and calcined in air at 650°C to remove the moisture and reaction carbon residue contained therein, and the obtained samples were denoted as XMC and FMC respectively.

Example 4

It is 30wt% to calculate by oxide dry basis solid content in the feed liquid, with the M sample of metering, silica sol (content 30wt%), aluminum sol (content 20%), calcium nitrate (content 23%), kaolin (content 85wt%) ) and the former powder of ZnAPSO-34 molecular sieve were added to a certain amount of deionized water in sequence, and stirred for 30 min (the oxide dry basis content of each raw material was respectively 70%, 7.5%, 3%, 1.5%, 9%, 9 %). The feed liquid is passed through a colloid mill for colloid milling, so that 70% of the particle diameters in the finally obtained slurry are less than 5 μm. The slurry is subjected to centrifugal spray drying, the rotational speed of the centrifugal atomizer is 30Hz, the inlet temperature is 400°C, and the outlet temperature is not lower than 120°C. The obtained spray-dried product was calcined in air at 650°C for 3 hours to obtain a microsphere catalyst, which was designated as M-1S.

Example 5

According to the batching ratio and preparation method in Example 4, the M samples were replaced by MC, XM, XMC, FM, and FMC samples respectively to prepare the catalyst. The obtained spray-dried products were calcined in air at 650°C for 3 hours to obtain microsphere catalysts, which were respectively denoted as MC-1S, XM-1S, XMC-1S, FM-1S, and FMC-1S.

Example 6

According to the calculation that the oxide dry base solid content in the feed liquid is 30wt%, the measured M sample, silica sol (content 30wt%), kaolin (content 85wt%) and SAPO-34 molecular sieve former powder are sequentially added to a certain amount of Stir in deionized water for 30 minutes (the oxide dry basis content of each raw material is respectively 30%, 14%, 21%, and 35%). The feed liquid is passed through a colloid mill for colloid milling, so that 70% of the particle diameters in the finally obtained slurry are less than 5 μm. The slurry is subjected to centrifugal spray drying, the rotational speed of the centrifugal atomizer is 30Hz, the inlet temperature is 400°C, and the outlet temperature is not lower than 120°C. The obtained spray-dried product was calcined in air at 650°C for 3 hours to obtain a microsphere catalyst, which was designated as M-2S.

Example 7

According to the batching ratio and preparation method in Example 6, the M samples were respectively replaced with MC, XM, XMC, FM, and FMC samples to prepare the catalyst. The obtained spray-dried products were calcined in air at 650°C for 3 hours to obtain microsphere catalysts, which were respectively denoted as MC-2S, XM-2S, XMC-2S, FM-2S, and FMC-2S.

Example 8

The catalyst samples obtained in Examples 1, 4, 5, 6, and 7 were subjected to wear index measurement, and the results are listed in Table 1. Several catalysts had low attrition indices.

Method for measuring wear index: put about 7g of catalyst sample in a gooseneck tube with an inner diameter of about 2.5cm, and humid air passes through the tube at a flow rate of 20L/min to provide a fluidized environment. The catalyst fine powder blown out from the catalyst was collected in a special filter bag, and the test was carried out for 4 hours. The attrition index is calculated according to the mass percentage lost per hour of the initial loading of the catalyst.

The particle size distribution of the catalyst was obtained by using a BT-9300 laser particle size distribution analyzer produced by Dandong Baite Instrument Co., Ltd. The results are shown in Table 2.

Example 9

Part of the catalysts obtained in Examples 1 and 5 were evaluated for the conversion of methanol to light olefins (MTO).

Evaluation conditions: Weigh 10g of the sample and load it into a fixed fluidized bed reactor. The sample is first activated at 550°C under 40ml/min nitrogen for half an hour, and then cooled to 450°C for chemical reaction. Stop nitrogen flow, feed with micropump, 40wt% methanol aqueous solution, weight space velocity WHSV is 2.0h ^-1 , the reaction product is analyzed by online gas chromatography, the results are shown in Table 3.

Table 1 Measurement of wear index of microsphere catalysts

Table 2 Particle size distribution of microsphere catalysts

samples Particle size distribution MC ＜20μm: 3.0% 20μm-40μm: 13.5% 40-80μm: 43.5% 80-120μm: 23.2% ＞120μm: 16.8% XM-1S ＜20μm: 0.5% 20μm-40μm: 8.1% 40-80μm: 48.3% 80-120μm: 25.7% ＞120μm: 17.4% MC-2S ＜20μm: 3.1% 20μm-40μm: 14.3% 40-80μm: 44.8% 80-120μm: 21.6% >120μm: 16.2% XM-2S ＜20μm: 2.4% 20μm-40μm: 15.8% 40-80μm: 43.3% 80-120μm: 22.3% >120μm: 16.2%

Table 3 Methanol conversion to olefins reaction results*

*Best reaction result when methanol is 100% converted

Claims (11)

1. a kind of recovery method of fluidized bed microsphere catalyst is that the catalyst to be reclaimed is mixed with each raw material of preparation fresh microsphere catalyst by a certain ratio, spray drying and high-temperature roasting after slurry colloid milling, can obtain relatively Microsphere catalyst with low wear index and suitable particle size distribution; its preparation process is as follows: 1) Mix the catalyst to be recovered with the original molecular sieve powder, binder, auxiliary agent, pore-forming agent and deionized water according to a certain oxide dry basis ratio, and make a slurry, and oxidize the recovered catalyst in the total batching The weight content of dry matter is not more than 80%; 2) The slurry is passed through a colloid mill, so that the diameter of the solid particles contained therein is less than 20 μm, 90% of the particle diameter is less than 10 μm, and 70% of the particle diameter is less than 5 μm; 3) spray drying to prepare microsphere samples; 4) Calcining the microsphere sample in an oxygen-containing atmosphere at 500-800° C. to obtain a microsphere catalyst for a fluidized bed. 2. according to the described method of claim 1, it is characterized in that the oxide dry basis weight content of the catalyst recovered in step 1) in the total batching is 10-80%. 3. according to the described method of claim 2, it is characterized in that step 1) described in the recovery catalyst active component is SAPO/MeAPSO molecular sieve. 4. The method according to claim 2, characterized in that the molecular sieve powder in step 1) is SAPO/MeAPSO molecular sieve. 5. The method according to claim 1, characterized in that the dry content of the binder in the total batching in the step 1) is 10-75%. 6. The method according to claim 1, characterized in that the oxide dry basis content of the auxiliary agent in the total batching in step 1) is 0-30%. 7. according to the described method of claim 1, it is characterized in that step 1) in the content of said scallop powder in total batching is 0-2%. 8. according to the method for claim 1, it is characterized in that step 3) adopts pressure type spray drying device or adopts centrifugal spray drying device. 9. The method according to claim 1, characterized in that the inlet temperature of the spray drying equipment in step 3) is 300-500°C, and the outlet temperature is not lower than 100°C. 10. according to the described method of claim 1, it is characterized in that the attrition index of the prepared microsphere catalyst is less than 2. 11. The microsphere catalyst prepared by the method according to claim 1 can be directly applied to the reaction of oxygenate conversion to olefin.