CN1128125C - Hydrogenation process for preparing cyclohexane by phase change method - Google Patents
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- CN1128125C CN1128125C CN 00111762 CN00111762A CN1128125C CN 1128125 C CN1128125 C CN 1128125C CN 00111762 CN00111762 CN 00111762 CN 00111762 A CN00111762 A CN 00111762A CN 1128125 C CN1128125 C CN 1128125C
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Abstract
The present invention discloses a technique for preparing cyclohexane by the hydrogenation of benzene by a phase-change method, which is operated by adopting a liquid-phase feeding method. A liquid phase is evaporated by heat release, so a liquid-phase zone, a mixed-phase zone and a gas-phase zone appear in order in a reactor, a catalyst goes through a completely wet state, a partially wet state, a completely dry state, etc. in order, and an integral reaction process also goes through the three procedures of a liquid-phase reaction, a heterogeneous reaction and a gas-phase reaction. The present invention has the advantages of simple equipment, low investment, high treatment capacity of the catalyst, high conversion rate of the benzene and easy operation control, and the present invention is a production technique for the preparation of the cyclohexane by the hydrogenation of the benzene with an industrialization prospect.
Description
The invention belongs to chemical engineering and basic field of chemical technology, relate to a kind of technology of prepared from benzene and hydrogen hexanaphthene.
Hexanaphthene is a kind of important Organic Chemicals, has purposes very widely, as being used to produce hexalin, pimelinketone and hexanodioic acid etc.At present, the production of hexanaphthene mainly contains the liquid-phase hydrogenatin technology of benzene and the gas phase hydrogenation technology of benzene, and has all experienced the important techniques innovation.The prepared from benzene and hydrogen hexanaphthene is a strong exothermal reaction, and reaction heat is 51.2kcal/mol, simultaneously, temperature of reaction must be controlled in the certain limit again, should be controlled at 300 ℃ (10bar) or below 330 ℃ (20bar),, avoid side reaction to take place simultaneously according to Theoretical Calculation to guarantee thoroughly conversion of reaction.
Liquid phase method by french petroleum research institute (IFP) exploitation, adopts pulverous Raney nickel as catalyzer at first, and temperature of reaction is 200-240 ℃, and pressure is 39.2bar.Whole reactor is made up of a Liquid-phase reactor and gas phase fixed-bed reactor.Reaction heat is taken away by Liquid-phase reactor, adopts pump that the mixture of benzene and cyclohexane is extracted out, enters interchanger, carries out thermal exchange with water, and the by-product low-pressure steam.The circulation of pump also can make catalyzer keep suspended state.Fixed bed does not move heat, but requires temperature rise to be no more than 30 ℃.For reaching this index, benzene concentration must be controlled at below 5% in the Liquid-phase reactor.For overcoming the wearing and tearing of catalyst powder foot couple recycle pump shaft envelope, simultaneously also in order to improve catalyst activity, IFP has developed the homogeneous phase complex catalyst again, and operational condition comparatively relaxes, and the design operation temperature is 189 ℃, and pressure is 29bar, and actual is 188 ℃ and 24bar.To become precipitation in case the defective of homogeneous phase complex catalyst is the catalyzer inactivation, and cause the wearing and tearing to the recycle pump shaft envelope, in addition, working pressure is than higher, and is unfavorable to keeping the safety in production;
Vapor phase process adopts calandria type fixed bed reactor, and benzene after the vaporization and hydrogen are being about 8 meters, carry out in the thousands of pipes that diameter is 34 millimeters, and temperature in is 140-160 ℃, and working pressure is 8bar.Reaction heat is removed by the water vapor in the chuck, the by-product low-pressure steam.Because the coupling connection problem between the non-linear character of fixed bed itself and heat transfer and the reaction, it is inevitable focus occurring.Emerging of focus causes side reaction to take place, and quality product descends.For avoiding this problem, fixed-bed reactor adopt the mode of dilute catalyst, and reaction speed plays the effect of optimizing the reactor operation.The main drawback of fixed bed operation is the equipment complexity, has the very big temperature difference between bed and chuck, and the parameter susceptibility is very high, the variation significantly of very big reactor behavior easily occurs with the minor fluctuations of operational condition;
Recently the catalytic distillation process of cutting down the hexanaphthene productive expense has been invented by CDtech company.Benzene adds the first distillation tower top, and hexanaphthene (containing＜10 μ g/g benzene) is obtained by the bottom of second tower.Hydrogen adds by two tower adverse currents, fills commercial catalysts in the tower.This technology is operated down for 149-204 ℃ at 14-17bar, and reaction heat makes tower remain on constant voltage by the overhead vapours control of circulating condensing.The security of this technology is better than fixed-bed process, and fixed bed needs a large amount of heat-obtainings.Lower service temperature has significantly reduced by product simultaneously, as the generation of methylcyclopentane.The investment cost of CDtech skilled industry device is than bed technology low 25%.But this technology still exists the higher defective of investment cost;
U.S. Texaco company has applied for fixed bed liquid-phase hydrogenatin patent USP5,198,233 (Feb.23,1993).This technology adopts two sections liquid-phase hydrogenatins, and first section catalyst activity is smaller, the chuck heat-obtaining, and 150 ℃ of jacket temperatures, catalyzer are the right cylinder of 1.6mm, the processing power of catalyzer is: 1.62 tons of benzene/(m
3Cat.hr).The subject matter that this technology exists is to move heat difficulty and high working pressure, has brought certain difficulty to operation.
In sum, though benzene hydrogenation prepares the at present existing multiple production technique of hexanaphthene, also having various weak points, a kind of new hydrogenation process for preparing cyclohexane is provided, is that institute of relevant branch of industry ten minutes is expected.
The object of the present invention is to provide a kind of hydrogenation process for preparing cyclohexane by phase change method, to overcome the existing existing above-mentioned defective of technology.
Design of the present invention is such:
In catalytic reaction process, the basis of katalysis is absorption, and the raw material that participates in reaction at first is adsorbed on the catalyzer, and then reacts, so heterogeneous catalytic reaction can be under the different wetting state at catalyzer fully and carries out.
The contriver thinks, for the strong heat release easy volatile of the such class of prepared from benzene and hydrogen hexanaphthene reaction system, as long as operating parameters is carried out optimized control, can adopt the liquid phase feeding mode to operate, make the liquid phase evaporation by heat release, make inside reactor occur liquid phase region-mixed phase district-gas phase zone successively, catalyzer experiences complete wetting-part successively wetting-states such as complete drying make entire reaction course also experience liquid phase reaction, inhomogeneous reaction and three processes of gas-phase reaction.This reaction process has the following advantages:
1 usefulness phase transformation vaporization heat is offset reaction heat, can solve effectively and move heat problem, saves heat-exchanger rig.
2 to answer the device inlet end be liquid phase, though reactant concn is higher, thermal discharge is bigger, and reaction heat can be evaporated heat and offset.Therefore compare with vapor phase process, material concentration can be much higher, thereby can add high throughput.
3 reaction later stages, most of reactant transformed, and heat release has not been a subject matter, added fast response and rise to principal contradiction, and reactant was gas phase this moment just, and the catalyst efficiency factor is improved.
4 compare with liquid phase method, and for hydrogenation reaction, hydrogen-oil ratio can descend.This is that hydrogen solubility is limited because under liquid phase state, and for the inversion of phases reactor, the reaction later stage has been converted into gas phase, and hydrogen does not exist dissolving and mass transfer problem, so hydrogen utilization ratio can be improved.
According to above-mentioned design, the contriver has proposed one and has been different from the operational path of the new preparation hexanaphthene of operational path in the past by a large amount of experiments and optimization computation, and concrete technological process is as described below:
Liquid benzene, thinner-hexanaphthene enter preheater after hydrogen mixes, make the temperature of this mixture rise to 130 ℃～170 ℃, the concentration of benzene is 14%～100% in the mixture, (molar percentage, down together), be preferably 16%～35%, said mixture enters bed with 3～6 hours-1 air speed from the fixed-bed reactor bottom, and working pressure is 1.0～3.0MPa;
The liquid benzene and the hydrogen that enter reactor promptly carry out strong exothermal reaction, generate hexanaphthene, and a large amount of heats that reaction is emitted make liquid benzene gasification, make reactor be in gas-liquid mixed phase state, catalyzer also is in the part wetting regime, owing to the vaporization of benzene has consumed reaction institute liberated heat, therefore, be unlikely to cause temperature of reaction too high and cause reaction conditions to worsen, reaction is proceeded, all vaporize until liquid benzene, make reactor be in gas phase state, catalyzer also is in the complete drying state.At this moment, most of reactant transforms, and heat release has not been a subject matter, and fast reaction speed rises to principal contradiction, and this moment, reactant was gas phase just, and the catalyst efficiency factor is improved;
The hot(test)-spot temperature of reactor is 260～285 ℃, except strictness control feeding temperature and concentration so that be reflected at carry out under the hot(test)-spot temperature, also can introduce the side line of one or more at the reactor middle part, introducing temperature is 10～30 ℃ the benzene and the mixture of hexanaphthene, increase the reactor regulating measure, avoid the bed overtemperature, the side line benzene concentration is 0～14%, if being higher than 14% will increase heat newly, be that present technique is undesirable;
Reaction product flows out bed from the fixed-bed reactor top, can obtain purity and be the hexanaphthene more than 99.7%.Also can further adopt conventional method collecting ring hexane from reaction product,,, can realize separating of hexanaphthene and hydrogen then by a gas-liquid separator as allowing the reaction product cooling.
The catalyzer that this reaction process adopts is for palladium content is 0.5%, carrier is Al
2O
3Catalyzer, this is a prior art, the present invention repeats no more.
Below will the invention will be further elaborated by accompanying drawing.
Fig. 1 is a schema of the present invention.
Fig. 2 is a reactor conditions synoptic diagram in the reaction process.Among the figure;
1---preheater 2---reactor
3---side line 4---water cooler
5---gas-liquid separator 6---liquid phase region
7---mixed phase district 8---gas phase zone
Benzene, thinner-hexanaphthene enter preheater 1 after hydrogen mixes, make the temperature of this mixture rise to 130 ℃～170 ℃, the concentration of benzene is 10%～100% in the mixture, (molar percentage, down together), be preferably 17%～35%, said mixture enters bed with 3～6 hours-1 air speed from fixed-bed reactor 2 bottoms, and working pressure is 1.0～3.0MPa;
The hot(test)-spot temperature of reactor 2 is 260～280 ℃, introduces two side lines 3 at reactor 2 middle parts, and introducing temperature is 10 ℃～30 ℃ the benzene and the mixture of hexanaphthene, increase reactor 2 regulating measures, avoid the bed overtemperature, the benzene concentration of side line 3 is 0～14%, (molar percentage);
Reaction product flows out bed from fixed-bed reactor 2 tops, is purity and is the gaseous state hexanaphthene more than 99.7%, also can enter a water cooler 4 again, reaction product is cooled, then by a gas-liquid separator 5, can realize separating of hexanaphthene and hydrogen, thereby obtain liquid hexanaphthene.Adopt conventional analytical procedure that reaction product is analyzed, the result shows that the transformation efficiency of benzene reaches as high as 100%.
As seen from Figure 2, there are three zones in said reactor in reaction process: reactor bottom is a liquid phase region, and the middle part is the mixed phase district, and top is gas phase zone.
With Comparative Examples the present invention is done detailed explanation by the following examples.
The structure of reactor parameter: reactor is a heat insulation-type, 20 millimeters of internal diameters, and the filling structure of bed is followed successively by: granulated glass sphere-catalyzer-granulated glass sphere.Catalyzer diameter 2～3mm, palladium content are 0.5%, and carrier is Al
2O
3, the catalyzer height is 1m, and the granulated glass sphere diameter is 5mm, and filling thickness is 30cm, plays distribution effect and buffering effect in bed;
Operational condition: system pressure 1.0Mpa, hydrogen flow rate 15.4 (standard liter/min), liquid speed 1.32 (kilogram/hour), 138 ℃ of wall temperatures, 136 ℃ of reactant entrance temperature, benzene concentration is 15.58% in the raw material.
Experimental result: the transformation efficiency of benzene is 100%, and top temperature is 269 ℃ in the reactor, can tentatively judge at bed height to be that the 90cm place enters gas phase state.The catalyst treatment ability is: 0.65 kilogram of benzene/kg catalyst hour.
Operational condition: system pressure 1.0MPa, hydrogen flow rate 15.4 (standard liter/min), liquid speed 1.32 (kilogram/hour), 158 ℃ of wall temperatures, 158 ℃ of reactant entrance temperature, benzene concentration is 16.6% in the raw material.Other condition with
Experimental result: the transformation efficiency of benzene is 100%, and top temperature is 270 ℃ in the reactor, can tentatively judge at bed height to be that the 60cm place enters gas phase state.The catalyst treatment ability is: 0.69 kilogram of benzene/kg catalyst hour.
Operational condition: system pressure 1.0 MPa, hydrogen flow rate 1 5.4 (standard liter/min), liquid speed 1.32 (kilogram/hour), 130 ℃ of wall temperatures, 130 ℃ of reactant entrance temperature, benzene concentration is 16.6% in the raw material.Other condition with
Experimental result: the transformation efficiency of benzene is 100%, and top temperature is 229 ℃ in the reactor, can tentatively judge at bed height to be that the 90cm place enters gas phase state.The catalyst treatment ability is: 0.69 kilogram of benzene/kg catalyst hour.
Operational condition: system pressure 1.0MPa, hydrogen flow rate 15.4 (standard liter/min), liquid speed 1.26 (kilogram/hour), 150 ℃ of wall temperatures, 150 ℃ of reactant entrance temperature, benzene concentration is 36.4% in the raw material.Other condition with
Experimental result: the transformation efficiency of benzene is 53.3%, and top temperature is 296 ℃ in the reactor, can tentatively judge at bed height to be that the 75cm place enters gas phase state.The catalyst treatment ability is: 0.77 kilogram of benzene/kg catalyst hour.
Operational condition: system pressure 1.0MPa, hydrogen flow rate 15.4 (standard liter/min), liquid speed 1.26 (kilogram/hour), 150 ℃ of wall temperatures, 150 ℃ of reactant entrance temperature, benzene concentration is 80.3% in the raw material.Other condition with
Experimental result: the transformation efficiency of benzene is 37.0%, and top temperature is 342 ℃ in the reactor, can tentatively judge at bed height to be that the 65cm place enters gas phase state.The catalyst treatment ability is: 1.18 kilograms of benzene/kg catalyst hour.
Operational condition: system pressure 1.0MPa, hydrogen flow rate 15.4 (standard liter/min), liquid speed 0.49 (kilogram/hour), 150 ℃ of wall temperatures, 150 ℃ of reactant entrance temperature, benzene concentration is 80.3% in the raw material.Other condition with
Experimental result: the transformation efficiency of benzene is 50.1%, and top temperature is 333 ℃ in the reactor, can tentatively judge at bed height to be that the 60cm place enters gas phase state.The catalyst treatment ability is: 0.62 kilogram of benzene/kg catalyst hour.
Operational condition: system pressure 1.0MPa, hydrogen flow rate 15.4 (standard liter/min), liquid speed 1.26 (kilogram/hour), 170 ℃ of wall temperatures, 170 ± 2 ℃ of reactant entrance temperature, benzene concentration is 16.6% in the raw material.Other condition is identical with embodiment 1.
Experimental result: the transformation efficiency of benzene is 100%, and top temperature is 308 ℃ in the reactor, can tentatively judge at bed height to be that the 55cm place enters gas phase state.The catalyst treatment ability is: 0.66 kilogram of benzene/kg catalyst hour.
Embodiment 8
Side line injects.Side line liquid material is a hexanaphthene, and 0.24 kilogram/hour of side line liquid speed adds point and is positioned at the 50cm place.Other condition is with embodiment 7.
Experimental result: the transformation efficiency of benzene is 100%, and top temperature is 285 ℃ in the reactor, and bed height is that the 55cm-65cm place is an isothermal section, and temperature is 229 ℃.The catalyst treatment ability is: 0.66 kilogram of benzene/kg catalyst hour.
Embodiment 9
Adopt the bilateral line.The concentration of benzene is 0 in the side line liquid material;
Operational condition: system pressure 1.0MPa, hydrogen flow rate 15.4 (standard liter/min), liquid speed 1.26 (kilogram/hour), 170 ℃ of wall temperatures, 170 ± 2 ℃ of reactant entrance temperature, benzene concentration is 36.4% in the raw material.Other condition is with embodiment 1.
Side line 1: 0.24 kilogram/hour of flow velocity is positioned at the 50cm place.
Side line 2: 0.18 kilogram/hour of flow velocity is positioned at the 80cm place.
Experimental result: the transformation efficiency of benzene is 100%, and top temperature is 288 ℃ in the reactor.The catalyst treatment ability is: 1.45 kilograms of benzene/kg catalyst hour.
Comparative Examples 1 adopts U.S. Pat P5, and the tubular reactor that the disclosed employing in 189,233 (Feb.23,1993) has chuck carries out the liquid phase benzene hydrogenation.Catalyzer divides two-layer filling, and bottom is the Ni-Cu-Cr oxide catalyst of diameter 4-5mm, and the upper strata is the aluminium oxide catalyst of diameter 1.5mm nickeliferous 47.5%.Jacket temperature is 149 ℃, working pressure 17.6MPa, and the catalyst treatment ability is: 1.62 kilograms of benzene/kg catalyst hour.
Comparative Examples 2
Adopt petroleum journal (refining of petroleum), 14 (1): the Powdered amorphous alloy catalyst under the rotatingfield effect that 41-45 (1998) is reported is the reformation light distillate hydrogenation of representative system to benzene/cyclohexane.Comparative Examples 1,2 and experiment parameter of the present invention and the results are shown in Table 1.
Benzene hydrogenation result under table 1 different reactor and the catalyzer condition
The result shows: (1) Comparative Examples 1 has adopted very high nickel content (40-80%) in order to improve catalyst activity, and catalyst activity composition of the present invention only is 0.5% palladium.(2) Comparative Examples 1 adopts chuck to move hot mode and can't solve scale-up problem, otherwise can only adopt the tubular structure of similar gas phase fixed bed.The present invention adopts insulation fix bed structure not have scale-up problem.
Can find that by contrast Comparative Examples is magnetic stablizing bed following deficiency: (3) inside reactor back-mixing problem is more serious, can not realize the thorough conversion of benzene.(4) catalyzer internal efficiency factor under liquid phase state is very low, and the pulverulence that must be 0.2mm could obtain the suitable catalytic capability of pellet type catalyst of the 2-3mm that adopts with the present invention.(5) pressure height and hydrogen-oil ratio height, the increase that brings cost of equipment and process cost.
Comparative Examples 3
Adopt petrochemical complex, 11 (1): many beds of employing prepared from benzene and hydrogen hexanaphthene technology of 30-33 (1982) report has obtained the economic and technical norms of optimizing by the catalyzer at different bed heights place filling different activities.In the presence of nickel catalyzator, reactor operating pressure is 2-2.5bar, and temperature is 110-150 ℃, and the hydrogen benzene molecular is than for (4.6-6: 1), the catalyst treatment ability is: 0.35-0.53 kilogram benzene/kg catalyst hour.
The defective of Comparative Examples 3 is, calandria type fixed bed complex structure has very high parameter susceptibility, and careless manipulation is prone to temperature control.By above-mentioned disclosed technical scheme and embodiment as seen, the present invention has very significant advantage, and equipment is simple, invest low, the processing power height of catalyzer, the transformation efficiency height of benzene, operation control is the production technique that a kind of benzene hydrogenation that industrial prospect arranged prepares hexanaphthene easily.
Claims (5)
1. hydrogenation process for preparing cyclohexane by phase change method is characterized in that:
Heating fluid benzene, the mixture to 130 of thinner-hexanaphthene and hydrogen ℃～170 ℃, the concentration of benzene is 14%～100% in the mixture, molar percentage, said mixture enters bed with 3～6 hours-1 air speed from the bottom of fixed-bed reactor (2), carry out the liquid-phase hydrogenatin reaction, working pressure is 1.0～3.0MPa, the hot(test)-spot temperature of reactor (2) is 260～280 ℃, be vaporizated into gasiform benzene further reacts with hydrogen by means of reaction heat, at last, reaction product flows out bed with gas form from fixed-bed reactor (2) top, can obtain hexanaphthene, and catalyzer is 0.5% for palladium content, carrier is Al
2O
3Catalyzer.
2. technology as claimed in claim 1 is characterized in that:
The heating of benzene, thinner-hexanaphthene and hydrogen mixture is carried out in preheater (1).
3. technology as claimed in claim 1 is characterized in that:
Reaction product is introduced into water cooler (4), and reaction product is cooled, and by gas-liquid separator (5), can obtain liquid cyclohexane then.
4. technology as claimed in claim 1 is characterized in that:
The concentration of benzene is 16%～35% in the mixture, molar percentage.
5. as the arbitrary described technology of claim 1-4, it is characterized in that:
Introduce one or more than one side lines (3) at reactor (2) middle part, introduce the mixture of benzene and hexanaphthene, the benzene concentration in the side line (3) is 0～14%.
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| CN 00111762 CN1128125C (en) | 2000-03-02 | 2000-03-02 | Hydrogenation process for preparing cyclohexane by phase change method |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1322922C (en) * | 2002-12-25 | 2007-06-27 | 南化集团研究院 | Platinum catalyst for preparing cyclohexane by hydrogenating benzene and its preparing process |
| CN101898930B (en) * | 2010-07-15 | 2013-11-20 | 山东华鲁恒升化工股份有限公司 | Device for producing cyclohexane by adding hydrogen in benzene and synthesis process |
| CN102432418B (en) * | 2011-09-07 | 2014-03-12 | 华东理工大学 | Method for preparing cyclohexane by performing two-section benzene hydrogenation in automatic liquid level control way |
| CN104525074B (en) * | 2014-12-17 | 2016-08-24 | 浙江华康药业股份有限公司 | The pH on-line control device of a kind of catalytic hydrogenation reaction and technique |
| CN107684929B (en) * | 2016-08-05 | 2020-12-22 | 中国石油化工股份有限公司 | Method for improving performance of benzene hydrogenation homogeneous catalyst |
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