Method and system for enhancing the settling separation of benzene hydrogenation catalyst by using temperature-resistant polymer flocculant

Abstract

This invention belongs to the field of catalyst separation technology and aims to solve the problems of low catalyst sedimentation efficiency, long recovery time, and resource loss after traditional benzene liquid-phase hydrogenation reactions. It provides a non-supported pure Ru catalyst enhanced sedimentation method and supporting system based on a heat-resistant polymeric flocculant, suitable for solid-liquid separation of benzene hydrogenation reaction feed at 120-160℃. This invention discloses a heat-resistant polymeric flocculant and its synthesis method. Using styrene-maleic anhydride copolymer (SMA) as the matrix, heat-resistant groups are grafted onto it, and chelating groups are introduced to obtain a modified polymeric flocculant. Through a "pretreatment-segmented sedimentation-catalyst regeneration" enhanced sedimentation process, along with a supporting sedimentation system, efficient solid-liquid separation of the benzene ring hydrogenation catalyst is achieved. The technical solution provided by this invention can significantly improve the Ru sedimentation rate and significantly shorten the sedimentation time, with an estimated reduction in recovery costs of about 10% compared to existing industrial processes.

Description

Technical Field

[0001] This invention relates to the field of catalyst separation technology, specifically to a method and system for enhancing sedimentation of a non-supported pure Ru catalyst based on a heat-resistant polymeric flocculant, suitable for solid-liquid separation of benzene hydrogenation reaction feed liquid at 120-160℃. Research Background

[0002] In the process of preparing cyclohexene / cyclohexane by benzene hydrogenation, unsupported Ru-based catalysts (particle size 2-10 nm) suffer from problems such as low sedimentation efficiency, long separation time, and resource loss due to their ultrafine particles and negative surface charge (Zeta potential -15 to -25 mV) in traditional sedimentation processes. Developing polymeric flocculants holds promise for solving the separation efficiency problem and reducing energy consumption.

[0003] Therefore, there is an urgent need to develop polymeric flocculants and process systems that are adapted to high-temperature conditions and can efficiently enhance sedimentation in the benzene hydrogenation process. Summary of the Invention

[0004] Technical goals

[0005] This technology aims to achieve efficient solid-liquid separation of benzene ring hydrogenation catalysts by designing a temperature-resistant polymeric flocculant. Specific technical indicators include: achieving a Ru particle settling rate of ≥95% at 120-160℃, with a settling time shortened to 30-60 min; high-temperature (160℃) stability of the flocculant ≥90%, with no molecular chain breakage; and a catalyst regeneration rate of ≥95% in the settling residue.

[0006] Technical solution

[0007] 1. Preparation of heat-resistant polymeric flocculants

[0008] Using styrene-maleic anhydride copolymer (SMA) as the matrix, SMA and aminosilane (APS, molar ratio 1:0.8-1.2) were reacted in N,N-dimethylformamide (DMF) at 80-100℃ for 4-6 h to introduce Si-O-Si bonds and enhance temperature resistance. Acrylic acid (AA, SMA to AA mass ratio 1:0.3-0.5) and ammonium persulfate (initiator, 0.5-1 wt%) were added to initiate polymerization, introducing carboxyl groups (-COOH) and amino groups (-NH2) to improve Ru... 2+ The chelating ability was improved; after precipitation with ethanol and vacuum drying at 60-80℃, a modified polymeric flocculant (named SMAS-g-AA) was obtained with a number average molecular weight of 500,000-800,000, a thermal weight loss rate of ≤10% at 160℃, and a water solubility of ≥30g / L.

[0009] 2. Enhance the settling process

[0010] The process employs a three-stage flow: pretreatment, staged settling, and catalyst regeneration. 1) The benzene hydrogenation reaction solution (containing 300-800 ppm Ru) is heated to 120-160℃, and 0.05-0.2 wt% SMAS-g-AA flocculant is added. The mixture is stirred at 150-250 r / min for 10-15 minutes to form 100-500 nm Ru-flocculant composite flocs. 2) A vertical staged settling tank (divided from top to bottom into a mixing zone, a flocculation zone, and a clarification zone) is used. The mixing zone is held for 10-15 minutes (maintaining 120-160℃), the flocculation zone for 20-30 minutes (stirring speed reduced to 50-80 r / min to promote floc growth), and the clarification zone for 10-15 minutes (allowing for settling and overflow of the supernatant). 3) 1-3 wt% NaOH is added to the settling residue (containing 10000-20000 ppm Ru). The solution was stirred at 80-100℃ for 30-60 minutes to remove surface flocculants and carbon deposits. After filtration, Ru catalyst was obtained with an activity recovery rate of ≥95%.

[0011] 3. Supporting Settlement System

[0012] The system includes a feed preheating tank (with a temperature control device, temperature control accuracy ±2℃); a vertical segmented settling tank (made of 316L stainless steel, with a paddle agitator in the mixing zone, baffles in the flocculation zone, and inclined tube packing in the clarification zone); a resin adsorption tower (with built-in D113 cation exchange resin and a backwashing device); a catalyst regeneration tank (with heating and stirring functions); and a DCS control system (real-time monitoring of temperature, stirring speed, and supernatant turbidity, and automatic adjustment of flocculant dosage). Beneficial effects

[0013] Efficiency breakthrough: The Ru particle settling rate has been increased from <60% to ≥95%, the settling time has been shortened from 4-6 hours to 30-60 minutes, the volume of the settling tank in the 200,000-ton unit has been reduced by 75%, and the land area and energy consumption have been reduced by more than 60%.

[0014] High temperature adaptability: The modified polymer flocculant has a thermal stability of ≥90% at 160℃, solving the problem of flocculant deactivation under high temperature conditions of benzene hydrogenation;

[0015] Resource recycling: Catalyst regeneration rate ≥95%, annual Ru loss reduced by 20-30 kg (for 200,000-ton-class plants), and solid waste emissions reduced by 70%;

[0016] Cost advantage: The flocculant dosage is only 0.05-0.2wt%, and the cost of treating 1 ton of liquid is reduced by 40-50% compared with membrane separation process. The equipment investment payback period is less than 1.2 years. Detailed Implementation

[0017] Example 1: Preparation of SMAS-g-AA flocculant

[0018] 100g SMA was dissolved in 500mL DMF, 80g APS was added, and the mixture was reacted at 90°C for 5h; then 40g AA and 0.8g ammonium persulfate were added, and the mixture was reacted at 85°C for 3h; after ethanol precipitation, the mixture was vacuum dried at 70°C for 8h to obtain SMAS-g-AA flocculant. The flocculant has a number-average molecular weight of 650,000, a thermal weight loss of 8.5% at 160°C, a water solubility of 35g / L, and a Zeta potential of +18mV.

[0019] During this operation, the single-pass conversion rate of bisphenol A reached 99.2%, the selectivity of hydrogenated bisphenol A reached 98.8%, and the reaction cycle was 4 hours. There was no hydrogen leakage during the system operation, and the temperature and pressure fluctuations were controlled within the set range. The energy consumption was reduced by 28% compared with the traditional stirred reactor of the same scale.

[0020] Example 2: Verification of Enhanced Settlement Technology

[0021] SMAS-g-AA prepared in Example 1 was used as the flocculant, with a dosage of 0.1 wt%. The pretreatment stirring speed was 200 r / min for 12 min, the residence time in the settling tank was 12 min in the mixing zone, 25 min in the flocculation zone (stirring at 80 r / min), and 13 min in the clarification zone. The resin column space velocity was 1.0 h⁻¹. -1 .

[0022] The results showed that the Ru particle settling rate was 96.5%, the turbidity of the supernatant was ≤5 NTU, and the settling time was 50 min; the Ru catalyst activity recovery rate after regeneration of the settling residue was 95.8%.

[0023] Compared with existing industrial production data, the Ru settling rate of the present invention is significantly improved, the settling time is significantly shortened, and the expected recycling cost is reduced by about 10%.

Claims

1. A method for sedimentation and separation of benzene ring hydrogenation catalyst enhanced by a heat-resistant polymeric flocculant, characterized in that, Includes the following steps: a) Pretreatment: Temperature 120-160°C o The benzene hydrogenation reaction solution of C (containing unsupported pure Ru catalyst) is mixed with a heat-resistant polymeric flocculant, wherein the flocculant is a modified product of styrene-maleic anhydride copolymer grafted with aminosilane and acrylic acid (SMAS-g-AA), the dosage is 0.05-0.2wt%, the stirring speed is 150-250r / min, the reaction time is 10-15min, and Ru-flocculant composite flocs are formed. b) Staged settling: The liquid obtained in step ① is sent to a vertical staged settling tank, and sequentially passes through the mixing zone (retention time 10-15 minutes, maintained at 120-160°C). o C) Flocculation zone (stay for 20-30 min, stirring speed 50-80 r / min), clarification zone (stay for 10-15 min, let stand), to obtain supernatant and sediment; c) Catalyst regeneration: Mix the sludge from step ② with a 1-3 wt% NaOH solution, and heat at 80-100°C. o Stir at C for 30-60 minutes, then filter to obtain the regenerated Ru catalyst.

2. The method according to claim 1, characterized in that, The preparation method of SMAS-g-AA in step ① is as follows: Styrene-maleic anhydride copolymer (SMA) and aminosilane (APS) are mixed in an N,N-dimethylformamide at a molar ratio of 1:0.8-1.2, and the mixture is heated to 80-100 mL of N,N-dimethylformamide. o React at step C for 4-6 hours, then add acrylic acid (SMA to acrylic acid mass ratio 1:0.3-0.5) and 0.5-1wt% ammonium persulfate, at 80-90°C. o The reaction proceeds for 3-5 hours at C, followed by ethanol precipitation and a final temperature of 60-80°C. o Obtained by vacuum drying at C.

3. The method according to claim 2, characterized in that, The number-average molecular weight of the SMAS-g-AA is 500,000-800,000, 160 o At temperature C, the thermal weight loss rate is ≤10%, the water solubility is ≥30g / L, and the Zeta potential is +15~+25mV.

4. The method according to claim 1, characterized in that, The vertical segmented settling tank mentioned in step ② is made of 316L stainless steel. The clarification zone has built-in inclined tube packing with an inclination angle of 60-75° and a packing spacing of 20-30mm.

5. The method according to claim 1, characterized in that, The activity recovery rate of the regenerated Ru catalyst in step ④ is ≥95%, and the Ru particle size is maintained at 1-2.6 nm.

6. A system for implementing the method of claim 1, characterized in that, The system includes a feed preheating tank, a vertical segmented settling tank, a resin adsorption tower, a catalyst regeneration tank, and a DCS control system, all connected in sequence. The feed preheating tank is equipped with a temperature control device with a temperature range of 120-160°C. o C, Temperature control accuracy ±2 o C; The vertical segmented settling tank is divided into a mixing zone (equipped with a paddle agitator), a flocculation zone (equipped with baffles), and a clarification zone (equipped with inclined tube packing) from top to bottom; The resin adsorption tower is equipped with D113 cation exchange resin and has a backwashing and desorption device; The DCS control system is connected to a temperature sensor, a turbidity sensor, and a stirring frequency converter, which can automatically adjust the flocculant dosage and stirring speed.

7. The system according to claim 6, characterized in that, The vertical segmented settling tank is equipped with heating jackets in both the mixing zone and the flocculation zone to maintain a temperature of 120-160℃.

8. The system according to claim 6, characterized in that, The catalyst regeneration tank is equipped with a heating device and an anchor-type agitator, and the stirring speed is adjustable (50-200 r / min).