CN112707803A - Method and system for preparing aldehyde by alcohol oxidation - Google Patents
Method and system for preparing aldehyde by alcohol oxidation Download PDFInfo
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- CN112707803A CN112707803A CN202011565637.7A CN202011565637A CN112707803A CN 112707803 A CN112707803 A CN 112707803A CN 202011565637 A CN202011565637 A CN 202011565637A CN 112707803 A CN112707803 A CN 112707803A
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 title claims abstract description 82
- 238000000034 method Methods 0.000 title claims abstract description 36
- 238000007254 oxidation reaction Methods 0.000 title claims abstract description 35
- 230000003647 oxidation Effects 0.000 title claims abstract description 25
- 125000002485 formyl group Chemical class [H]C(*)=O 0.000 title claims abstract 15
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 387
- 229910052709 silver Inorganic materials 0.000 claims abstract description 387
- 239000004332 silver Substances 0.000 claims abstract description 387
- 239000003054 catalyst Substances 0.000 claims abstract description 376
- 230000001590 oxidative effect Effects 0.000 claims abstract description 44
- 239000007800 oxidant agent Substances 0.000 claims abstract description 41
- 238000011049 filling Methods 0.000 claims abstract description 28
- 238000010521 absorption reaction Methods 0.000 claims abstract description 25
- 239000000463 material Substances 0.000 claims abstract description 25
- 238000006243 chemical reaction Methods 0.000 claims abstract description 15
- 239000002250 absorbent Substances 0.000 claims abstract description 13
- 230000002745 absorbent Effects 0.000 claims abstract description 13
- 239000007789 gas Substances 0.000 claims description 121
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 58
- 229910052802 copper Inorganic materials 0.000 claims description 58
- 239000010949 copper Substances 0.000 claims description 58
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 45
- 229910052751 metal Inorganic materials 0.000 claims description 24
- 239000002184 metal Substances 0.000 claims description 24
- 239000002245 particle Substances 0.000 claims description 21
- 239000012535 impurity Substances 0.000 claims description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical group [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 9
- 239000001301 oxygen Substances 0.000 claims description 9
- 229910052760 oxygen Inorganic materials 0.000 claims description 9
- 238000001914 filtration Methods 0.000 claims description 6
- 230000008569 process Effects 0.000 claims description 6
- 238000009826 distribution Methods 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 4
- 238000004804 winding Methods 0.000 claims description 3
- 125000004432 carbon atom Chemical group C* 0.000 claims description 2
- 238000004891 communication Methods 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 17
- 238000000746 purification Methods 0.000 abstract description 3
- 230000015572 biosynthetic process Effects 0.000 abstract description 2
- 150000001875 compounds Chemical class 0.000 abstract description 2
- 238000003786 synthesis reaction Methods 0.000 abstract description 2
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 57
- 239000010410 layer Substances 0.000 description 56
- 150000001299 aldehydes Chemical class 0.000 description 35
- 239000000243 solution Substances 0.000 description 13
- 238000004519 manufacturing process Methods 0.000 description 9
- 230000008929 regeneration Effects 0.000 description 8
- 238000011069 regeneration method Methods 0.000 description 8
- 238000011068 loading method Methods 0.000 description 6
- 230000002035 prolonged effect Effects 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 230000003197 catalytic effect Effects 0.000 description 4
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000012423 maintenance Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 239000000376 reactant Substances 0.000 description 3
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 2
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 2
- RRHGJUQNOFWUDK-UHFFFAOYSA-N Isoprene Chemical compound CC(=C)C=C RRHGJUQNOFWUDK-UHFFFAOYSA-N 0.000 description 2
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000006356 dehydrogenation reaction Methods 0.000 description 2
- 235000019253 formic acid Nutrition 0.000 description 2
- 239000008235 industrial water Substances 0.000 description 2
- KWUUWVQMAVOYKS-UHFFFAOYSA-N iron molybdenum Chemical compound [Fe].[Fe][Mo][Mo] KWUUWVQMAVOYKS-UHFFFAOYSA-N 0.000 description 2
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 231100000614 poison Toxicity 0.000 description 2
- 231100000572 poisoning Toxicity 0.000 description 2
- 230000000607 poisoning effect Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- PCSMJKASWLYICJ-UHFFFAOYSA-N Succinic aldehyde Chemical compound O=CCCC=O PCSMJKASWLYICJ-UHFFFAOYSA-N 0.000 description 1
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 1
- ZJCCRDAZUWHFQH-UHFFFAOYSA-N Trimethylolpropane Chemical compound CCC(CO)(CO)CO ZJCCRDAZUWHFQH-UHFFFAOYSA-N 0.000 description 1
- 229920001807 Urea-formaldehyde Polymers 0.000 description 1
- 229920002978 Vinylon Polymers 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 230000001476 alcoholic effect Effects 0.000 description 1
- 150000001335 aliphatic alkanes Chemical class 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- NKDDWNXOKDWJAK-UHFFFAOYSA-N dimethoxymethane Chemical compound COCOC NKDDWNXOKDWJAK-UHFFFAOYSA-N 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 230000002779 inactivation Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 239000010954 inorganic particle Substances 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000003915 liquefied petroleum gas Substances 0.000 description 1
- 159000000003 magnesium salts Chemical class 0.000 description 1
- 239000011859 microparticle Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 229910052755 nonmetal Inorganic materials 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 239000002304 perfume Substances 0.000 description 1
- 239000002574 poison Substances 0.000 description 1
- 230000007096 poisonous effect Effects 0.000 description 1
- ODGAOXROABLFNM-UHFFFAOYSA-N polynoxylin Chemical compound O=C.NC(N)=O ODGAOXROABLFNM-UHFFFAOYSA-N 0.000 description 1
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
- C07C45/32—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen
- C07C45/37—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of >C—O—functional groups to >C=O groups
- C07C45/38—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of >C—O—functional groups to >C=O groups being a primary hydroxyl group
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
- B01J8/04—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds
- B01J8/0446—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds the flow within the beds being predominantly vertical
- B01J8/0476—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds the flow within the beds being predominantly vertical in two or more otherwise shaped beds
- B01J8/048—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds the flow within the beds being predominantly vertical in two or more otherwise shaped beds the beds being superimposed one above the other
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
- C07C45/783—Separation; Purification; Stabilisation; Use of additives by gas-liquid treatment, e.g. by gas-liquid absorption
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Catalysts (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to the technical field of compound synthesis, in particular to a method and a system for preparing aldehyde by alcohol oxidation. The method comprises the following steps: (1) distributing and rectifying the filtered alcohol, the filtered oxidant and the steam to obtain a mixed material; (2) under the condition of alcohol oxidation, enabling the mixed material to flow through a silver catalyst bed from bottom to top to carry out alcohol oxidation reaction to obtain aldehyde-containing gas; (3) contacting the aldehyde-containing gas with an absorbent for absorption to obtain an aldehyde-containing solution and a tail gas, dividing the tail gas into a circulating gas and a residual gas, and returning the circulating gas to the steam in the step (1), wherein the volume flow ratio of the circulating gas to the residual gas is 10-40: 60-90. The invention combines the filling rule characteristic of the silver catalyst bed with the purification of reaction materials, improves the activity of the silver catalyst and prolongs the service life of the silver catalyst.
Description
Technical Field
The invention relates to the technical field of compound synthesis, in particular to a method and a system for preparing aldehyde by alcohol oxidation.
Background
Formaldehyde is an important basic organic raw material, is mostly used as a raw material for producing resin in the chemical industry, and is secondly used for producing products such as vinylon, 1, 4-butanedialdehyde, trimethylolpropane, pyridine, isoprene and the like. In addition, formaldehyde can be used in the fields of synthetic perfumes, paper treating agents, fuel auxiliaries, medical supplies and the like, and can also be used as a urea-formaldehyde type corrosion inhibition fertilizer in agriculture.
At present, the production methods of formaldehyde mainly include a methanol oxidation method, an alkane direct oxidation method, a dimethyl ether oxidation method, a non-catalytic oxidation method using liquefied petroleum gas as a raw material, a methylal oxidation method and the like. The production of industrial formaldehyde generally adopts a methanol oxidation method, and mainly comprises an iron-molybdenum method and a silver method: the iron-molybdenum method is mainly used for producing 37-55% formaldehyde, although the unit consumption of methanol is low by adopting the method, the content of methanol in the product is low, the acid value of the product is higher, the investment is large, and the energy consumption is too high; the silver method has low power consumption, small investment and low formic acid content in the product, but the unit consumption of methanol is high, and the formaldehyde contains a certain part of methanol, which is not favorable for reducing the cost and the purity of the formaldehyde and has certain limitation on the production.
CN202576298U discloses a low system resistance formaldehyde production process unit, wherein, silver catalyst layer in the oxidation reaction tower is divided into three layers, the particle size range of each layer of silver catalyst from bottom to top is respectively 4-6mm, 3-4mm and 2-3mm, namely, the particle mesh number of the silver catalyst is increased from bottom to top in turn, and the total packing height of the silver catalyst layer is 80-100 mm.
CN1537673A discloses a supported silver catalyst for preparing anhydrous formaldehyde by direct dehydrogenation of methanol, which is prepared by a sol-gel method, and specifically comprises: a certain amount of ethyl orthosilicate is mixed with aqueous solution or alcoholic solution containing soluble magnesium salt and aluminum salt, and then the mixture is dripped into inorganic silver salt aqueous solution, and the catalyst is prepared by steps of gelling, aging, drying, roasting and the like.
In view of the close correlation between the silver catalyst bed and the silver catalyst utilization rate, a new method for preparing aldehyde by alcohol oxidation is urgently needed, the activity of the silver catalyst can be effectively released and improved, the loss of the silver catalyst is reduced, the regeneration period of the silver catalyst is prolonged, abnormal shutdown is reduced, the cost is saved, the consumption is reduced, and the production efficiency is improved.
Disclosure of Invention
The invention aims to solve the problems of low activity, large loss, short regeneration period, more side reactions of a silver catalyst bed layer, unstable operation and the like of a silver catalyst in the prior art for preparing formaldehyde, and provides a method and a system for preparing aldehyde by alcohol oxidation, wherein the method effectively improves the catalytic activity and the regeneration period of the silver catalyst; meanwhile, the system ensures stable and high-quality production of formaldehyde.
In order to achieve the above object, a first aspect of the present invention provides a method for producing an aldehyde by oxidizing an alcohol, the method comprising the steps of:
(1) distributing and rectifying the filtered alcohol, the filtered oxidant and the steam to obtain a mixed material;
(2) under the condition of alcohol oxidation, enabling the mixed material to flow through a silver catalyst bed from bottom to top to carry out alcohol oxidation reaction to obtain aldehyde-containing gas;
(3) contacting the aldehyde-containing gas with an absorbent for absorption to obtain an aldehyde-containing solution and tail gas, dividing the tail gas into a circulating gas and a residual gas, and returning the circulating gas to the steam in the step (1);
wherein the volume flow ratio of the circulating gas to the residual gas is 10-40: 60-90 parts of;
wherein the silver catalyst bed comprises at least two stacked silver catalyst beds filled with silver catalyst in the following manner: according to the direction from bottom to top of the silver catalyst bed layer, the particle size and the filling quality of the silver catalyst are reduced in sequence.
In a second aspect, the present invention provides a system for preparing aldehyde by oxidizing alcohol, comprising: a quaternary mixer, a reactor containing a silver catalyst bed and an absorption tower which are communicated in sequence,
the quaternary mixer is used for distributing and rectifying the filtered alcohol, the filtered oxidant and the steam to obtain a mixed material;
the reactor is used for enabling the mixed material to flow through the silver catalyst bed from bottom to top to carry out alcohol oxidation reaction to obtain aldehyde-containing gas;
the absorption tower is used for contacting the aldehyde-containing gas with an absorbent for absorption to obtain an aldehyde-containing solution and tail gas, and the tail gas is divided into circulating gas and residual gas;
wherein a circulating gas outlet of the absorption tower is communicated with an inlet of the quaternary mixer and is used for returning the circulating gas to the quaternary mixer;
wherein the silver catalyst bed comprises at least two stacked silver catalyst beds filled with silver catalyst in the following manner: according to the direction from bottom to top of the silver catalyst bed layer, the particle size and the filling quality of the silver catalyst are reduced in sequence.
Compared with the prior art, the invention has the following advantages:
(1) according to the invention, by limiting the regular characteristics of the particle size and the filling quality of the silver catalyst in each silver catalyst bed layer (namely, the silver catalyst bed comprises at least two stacked silver catalyst bed layers, and the silver catalyst filled in the silver catalyst bed layers in the following way is filled in the silver catalyst bed layers, the particle size and the filling quality of the silver catalyst are sequentially reduced according to the direction from bottom to top of the silver catalyst bed layers, the improper loss of the silver catalyst can be effectively reduced, the system resistance in a reactor is reduced, the adhesion of the silver catalyst bed layers is avoided, the activity of the silver catalyst is fully released, and the regeneration period of the silver catalyst is prolonged;
(2) by adopting the method provided by the invention, the continuous operation period of a single formaldehyde reactor is up to 42 days; meanwhile, the economic cost of silver catalyst loss and replacement is reduced, so that the frequency of annual parking maintenance (namely silver catalyst replacement) is reduced;
(3) the invention combines the filling rule characteristic of the silver catalyst bed with the purification of reaction materials, improves the activity of the silver catalyst and prolongs the service life of the silver catalyst.
Drawings
FIG. 1 is a schematic view of a system for preparing aldehyde by oxidizing alcohol according to the present invention.
Fig. 2 is a schematic structural diagram of a gas distributor in a quaternary mixer provided by the present invention.
Description of the reference numerals
1. Alcohol 2, oxidant 3, steam
4. Mixed material 5, silver catalyst bed 6, aldehyde-containing gas
7. Absorbent 8, aldehyde-containing solution 9 and tail gas
10. Circulating gas 11, residual gas I and alcohol filter
II. Oxidant filter III, quaternary mixer IV and reactor
V, absorption tower
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
In the present invention, the "top" of the container referred to in the specification means 0 to 10% of the position of the container from the top to the bottom without specific description; the "upper part" of the container means 0-30% of the position of the container from top to bottom; the "lower part" of the container means 70-100% of the position of the container from top to bottom; the "bottom" of the container means 90-100% of the container from top to bottom.
The first aspect of the invention provides a method for preparing aldehyde by oxidizing alcohol, which comprises the following steps:
(1) distributing and rectifying the filtered alcohol, the filtered oxidant and the steam to obtain a mixed material;
(2) under the condition of alcohol oxidation, enabling the mixed material to flow through a silver catalyst bed from bottom to top to carry out alcohol oxidation reaction to obtain aldehyde-containing gas;
(3) contacting the aldehyde-containing gas with an absorbent for absorption to obtain an aldehyde-containing solution and tail gas, dividing the tail gas into a circulating gas and a residual gas, and returning the circulating gas to the steam in the step (1);
wherein the volume flow ratio of the circulating gas to the residual gas is 10-40: 60-90 parts of;
wherein the silver catalyst bed comprises at least two stacked silver catalyst beds filled with silver catalyst in the following manner: according to the direction from bottom to top of the silver catalyst bed layer, the particle size and the filling quality of the silver catalyst are reduced in sequence.
The inventor of the invention discovers that the filling quality and the particle size of the silver catalyst in each silver catalyst bed layer are combined and proportioned according to the actual production requirement, and the silver catalyst beds can be adjusted and optimized at any time according to the change of the production condition, so that the proper silver catalyst beds can be obtained; specifically, the silver catalyst bed comprises at least two silver catalyst beds which are stacked from bottom to top, and the silver catalyst beds are filled with silver catalysts; in the silver catalyst bed layer, the particle size of the silver catalyst is reduced from bottom to top in sequence, and the filling quality of the silver catalyst is reduced from bottom to top in sequence.
According to a preferred embodiment of the present invention, the volume flow ratio of the recycle gas to the residual gas is 10 to 30: 70-90. The preferable conditions are adopted, so that the regeneration period of the silver catalyst is more favorably prolonged, and the service life of the silver catalyst is prolonged.
According to the present invention, preferably, the volume ratio of the filtered alcohol, the filtered oxidant, the steam and the recycle gas is 1: 0.25-0.55: 0.2-1: 1-2, preferably 1: 0.36-0.44: 0.5-0.8: 1.2-1.5. The preferable conditions are adopted, so that the conversion rate of the alcohol and the selectivity of the aldehyde are improved.
In the invention, in order to improve the influence of reactants on the activity of the silver catalyst to cause the deactivation of the catalyst poisoning or the reduction of the activity, the alcohol and the oxidant are respectively and independently filtered, preferably, the content of solid impurities in the filtered alcohol is less than or equal to 0.01 weight percent, wherein the solid impurities refer to inorganic particles; the content of impurities in the filtered oxidant is less than or equal to 0.01 wt%, wherein the impurities refer to inorganic matter micro particles, trace acid gas, water and the like.
In the invention, the filtered alcohol and the filtered oxidant are adopted, so that the impurity content in the alcohol and the oxidant is obviously reduced, the influence of impurities in the alcohol and the oxidant on the activity of the silver catalyst is eliminated, and the activity of the silver catalyst is improved, thereby prolonging the service life of the silver catalyst.
In the present invention, the alcohol is not particularly limited, and preferably the alcohol has 1 to 5 carbon atoms. Further preferably, the alcohol is methanol and/or ethanol.
In the present invention, the oxidizing agent is selected from a wide range so as to be able to effect oxidation of an alcohol, and preferably, the oxidizing agent is an oxygen-containing gas. Specifically, the oxygen-containing gas contains oxygen in an amount of not less than 5% by volume. Preferably, the oxidant is oxygen and/or air, more preferably air.
In the invention, in the step (1), the distribution rectification refers to rectifying the filtered alcohol, the filtered oxidant, the steam and the circulating gas to solve the problem of loss of a precision filter element caused by bias flow of the gas, so that the filtering effect is reduced, and impurities enter the reactor to cause poisoning and inactivation of the silver catalyst or reduction of activity.
According to the invention, the distribution rectification is preferably performed in a quaternary mixer provided with a gas distributor of an umbrella-shaped support structure, and the central axis of the gas distributor coincides with the central axis of the quaternary mixer.
Preferably, the angle α between the extending direction of the umbrella-shaped support structure and the central axis of the gas distributor is 30-45 °. The purpose of setting up like this is to avoid the loss of accurate filter core, improves the filter effect to improve the activity of silver catalyst.
In the present invention, the alcohol oxidation conditions are widely selected so long as the alcohol is oxidized to the aldehyde. Preferably, the alcohol oxidation conditions include: the reaction temperature is 600-700 ℃, preferably 630-650 ℃; the reaction pressure is less than or equal to 50kPa, preferably 35 to 50 kPa.
Preferably, the filtered alcohol, the filtered oxidant, the steam and the recycle gas are each independently subjected to a heat-preserving treatment prior to the rectification of the distribution. The preferable conditions are adopted, so that the blackening phenomenon of the surface layer of the silver catalyst is obviously reduced, the catalytic activity is improved, and the service life is prolonged.
According to a preferred embodiment of the present invention, the filtered oxidant and the recycle gas are separately heat-preserved with 0.1-0.8MPa steam.
According to a preferred embodiment of the present invention, the filtered alcohol and the steam are separately subjected to the heat-retaining treatment using 0.2 to 0.4MPa steam.
According to the present invention, the silver catalyst is not particularly limited, and various catalysts using silver as an active site used in the process of producing aldehyde by oxidizing alcohol can be used. Preferably, the silver catalyst is a metallic silver catalyst. Further preferably, the metallic silver catalyst is selected from at least one of electrolytic silver, sponge silver and crystalline silver, more preferably electrolytic silver.
In the present invention, the shape of the electrolytic silver is not particularly limited. Preferably, the electrolytic silver is in the form of irregular silver particles.
Preferably, the mesh number of the silver catalyst is 5 to 100 meshes, and more preferably 10 to 60 meshes.
Preferably, the silver catalyst bed comprises 2 to 6 silver catalyst beds.
According to the present invention, preferably, in two adjacent silver catalyst beds, the particle size of the silver catalyst loaded in the silver catalyst bed disposed above is smaller than the particle size of the silver catalyst loaded in the silver catalyst bed disposed below; the loading mass of the silver catalyst in the silver catalyst bed arranged above is smaller than that in the silver catalyst bed arranged below.
According to the invention, preferably, the silver catalyst bed comprises two silver catalyst beds which are arranged in parallel from bottom to top in sequence, the particle size of the silver catalyst in the two silver catalyst beds is reduced from bottom to top in sequence, and the filling quality of the silver catalyst is reduced from bottom to top in sequence.
According to a preferred embodiment of the present invention, when the silver catalyst bed comprises 2 silver catalyst beds, the loading mass of the silver catalyst in the two silver catalyst beds is 51 to 99 wt%, 1 to 49 wt%, preferably 55 to 90 wt%, 10 to 45 wt%, more preferably 60 to 70 wt%, and 30 to 40 wt%, respectively, based on the total amount of the silver catalyst loaded in the silver catalyst bed from bottom to top.
According to a preferred embodiment of the present invention, when the silver catalyst bed comprises two silver catalyst beds, from bottom to top, the mesh number of the silver catalyst in the two silver catalyst beds is 5-40 mesh, 40-100 mesh, preferably 10-30 mesh, 40-60 mesh, respectively.
According to the invention, preferably, the silver catalyst bed comprises three silver catalyst beds, the three silver catalyst beds are arranged in parallel from bottom to top in sequence, the particle sizes of the silver catalysts in the three silver catalyst beds are reduced from bottom to top in sequence, and the filling mass of the silver catalysts is reduced from bottom to top in sequence.
According to a preferred embodiment of the present invention, when the silver catalyst bed comprises 3 silver catalyst beds, the loading mass of the silver catalyst in the three silver catalyst beds from bottom to top is 40-60 wt%, 30-40 wt%, 10-20 wt%, preferably 50-60 wt%, 30-35 wt%, 10-15 wt%, based on the total amount of the silver catalyst loaded in the silver catalyst bed.
According to a preferred embodiment of the present invention, when the silver catalyst bed comprises three silver catalyst beds, from bottom to top, the mesh number of the silver catalyst in the three silver catalyst beds is 5-30 mesh, 30-40 mesh, 40-100 mesh, preferably 10-30 mesh, 30-40 mesh, 40-60 mesh.
According to the invention, preferably, the silver catalyst bed comprises four silver catalyst beds, the four silver catalyst beds are arranged in parallel from bottom to top in sequence, the particle sizes of the silver catalysts in the four silver catalyst beds are reduced from bottom to top in sequence, and the filling mass of the silver catalysts is reduced from bottom to top in sequence.
According to a preferred embodiment of the present invention, when the silver catalyst bed comprises 4 silver catalyst beds, the loading mass of the silver catalyst in the four silver catalyst beds is 45-65 wt%, 20-30 wt%, 10-20 wt%, 5-10 wt%, preferably 50-60 wt%, 20-27 wt%, 15-18 wt%, 5-8 wt%, based on the total amount of the silver catalyst loaded in the silver catalyst bed, from bottom to top, respectively.
According to a preferred embodiment of the present invention, when the silver catalyst bed comprises four silver catalyst beds, from bottom to top, the mesh number of the silver catalyst in the four silver catalyst beds is 5-15 mesh, 15-35 mesh, 35-45 mesh, 45-100 mesh, preferably 10-15 mesh, 15-35 mesh, 35-45 mesh, 45-60 mesh.
According to the present invention, preferably, the silver catalyst bed comprises five silver catalyst beds, the five silver catalyst beds are sequentially arranged in parallel from bottom to top, the particle size of the silver catalyst in the five silver catalyst beds is sequentially reduced from bottom to top, and the filling mass of the silver catalyst is sequentially reduced from bottom to top.
According to a preferred embodiment of the present invention, when the silver catalyst bed comprises 5 silver catalyst beds, the loading mass of the silver catalyst in five silver catalyst beds from bottom to top based on the total amount of the silver catalyst loaded in the silver catalyst bed is 40 to 60 wt%, 15 to 30 wt%, 10 to 15 wt%, 5 to 10 wt%, 1 to 5 wt%, preferably 45 to 55 wt%, 20 to 25 wt%, 10 to 15 wt%, 8 to 10 wt%, 1 to 5 wt%, respectively.
According to a preferred embodiment of the present invention, when the silver catalyst bed comprises five silver catalyst beds, from bottom to top, the mesh number of the silver catalyst in the five silver catalyst beds is 5-15 mesh, 15-25 mesh, 25-35 mesh, 35-45 mesh, 45-100 mesh, preferably 10-15 mesh, 15-25 mesh, 25-35 mesh, 35-45 mesh, 45-60 mesh.
According to the present invention, preferably, the silver catalyst bed comprises six silver catalyst beds, the six silver catalyst beds are sequentially arranged in parallel from bottom to top, the particle sizes of the silver catalysts in the six silver catalyst beds are sequentially reduced from bottom to top, and the filling mass of the silver catalysts is sequentially reduced from bottom to top.
According to a preferred embodiment of the present invention, when the silver catalyst bed comprises 6 silver catalyst beds, the loading mass of the silver catalyst in the six silver catalyst beds is 35 to 50 wt%, 20 to 35 wt%, 13 to 20 wt%, 8 to 13 wt%, 5 to 8 wt%, 1 to 5 wt%, preferably 40 to 45 wt%, 20 to 30 wt%, 13 to 15 wt%, 10 to 13 wt%, 5 to 8 wt%, 1 to 5 wt%, based on the total amount of the silver catalyst loaded in the silver catalyst bed, from bottom to top, respectively.
According to a preferred embodiment of the present invention, when the silver catalyst bed comprises six silver catalyst beds, from bottom to top, the mesh number of the silver catalyst in the six silver catalyst beds is 5-15 mesh, 15-20 mesh, 20-30 mesh, 30-40 mesh, 40-50 mesh, 50-100 mesh, preferably 10-15 mesh, 15-20 mesh, 20-30 mesh, 30-40 mesh, 40-50 mesh, 50-60 mesh.
According to the present invention, preferably, the silver catalyst bed is further provided with a metal backing mesh. Further preferably, the metal backing net is a copper backing net. Copper and silver are elements of the same group, and copper has less metal activity than silver. The invention adopts copper as the supporting net, on one hand, the silver can be supported and lined, so that the silver can well participate in the catalytic reaction, and on the other hand, the copper only plays a role of supporting and lining and does not participate in the catalytic reaction.
In the invention, the selection range of the number of the metal supporting nets is wide. Preferably, the number of the metal supporting nets is 1-10, more preferably 1-5, even more preferably 2-4, such as 2, 3, 4.
In the present invention, the metal supporting mesh is not particularly limited in its arrangement, and is disposed at a distance from the silver catalyst bed layer, and/or is disposed below the bottommost silver catalyst bed layer of the silver catalyst bed.
In the present invention, the term "spaced arrangement" means that when the number of the silver catalyst beds and the metal supporting nets is plural, one silver catalyst bed, one metal supporting net … … are alternately arranged, or a plurality of silver catalyst beds (Z1-Z2-Z3 … ZN), one metal supporting net, a plurality of silver catalyst beds (Z1-Z2-Z3 … ZN), one metal supporting net … … are alternately arranged, or a plurality of silver catalyst beds (Z1-Z2-Z3 … ZN), a plurality of metal supporting nets (R1-R2-R3 … RN), a plurality of silver catalyst beds (Z1-Z2-Z3 … ZN), a plurality of metal supporting nets (R1-R2-R3 … RN) … … are alternately arranged.
According to a preferred embodiment of the present invention, the metal backing mesh is disposed below a bottommost silver catalyst bed layer of the silver catalyst bed. By adopting the arrangement mode, the reactant can be better and more uniformly distributed in the process of flowing upwards from the bottom of the silver catalyst bed, so that the reactant is fully contacted and reacted with the silver catalyst bed. If the interval arrangement is adopted, reaction is easy to be unstable and inclined after a period of time, and the distribution is not uniform.
Further preferably, the metal supporting and lining nets are stacked from bottom to top, and the mesh number of the metal supporting and lining nets is increased from bottom to top. By adopting the method of stacking and paving the copper support screen, the problem that the silver catalyst is adhered to the copper screen can be effectively solved, and the loss of the silver catalyst is reduced.
According to a preferred embodiment of the invention, a copper support net is arranged below the bottommost silver catalyst bed layer of the silver catalyst bed, the copper support net is sequentially stacked and paved from bottom to top, and the mesh number of the copper support net is sequentially increased from bottom to top.
According to an embodiment of the invention, the copper supporting net is formed by sequentially stacking three copper nets with specifications of 2 meshes (lower layer), 5 meshes (middle layer) and 50 meshes (upper layer).
In the present invention, the absorbent has a wide range of choice as long as the aldehyde in the aldehyde-containing gas is absorbed. Preferably, the absorbent is selected from at least one of industrial water, condensed water and desalinated water, preferably industrial water.
In a second aspect, the present invention provides a system for preparing aldehyde by oxidizing alcohol, comprising: a quaternary mixer, a reactor containing a silver catalyst bed and an absorption tower which are communicated in sequence,
the quaternary mixer is used for distributing and rectifying the filtered alcohol, the filtered oxidant and the steam to obtain a mixed material;
the reactor is used for enabling the mixed material to flow through the silver catalyst bed from bottom to top to carry out alcohol oxidation reaction to obtain aldehyde-containing gas;
the absorption tower is used for contacting the aldehyde-containing gas with an absorbent for absorption to obtain an aldehyde-containing solution and tail gas, and the tail gas is divided into circulating gas and residual gas;
wherein a circulating gas outlet of the absorption tower is communicated with an inlet of the quaternary mixer and is used for returning the circulating gas to the quaternary mixer;
wherein the silver catalyst bed comprises at least two stacked silver catalyst beds filled with silver catalyst in the following manner: according to the direction from bottom to top of the silver catalyst bed layer, the particle size and the filling quality of the silver catalyst are reduced in sequence.
In the present invention, the arrangement of the silver catalyst bed is defined as above without specific description, and the present invention will not be described in detail.
According to the invention, preferably, the lower part of the absorption tower is communicated with the upper part of the reactor and is used for contacting the aldehyde-containing gas with an absorbent for absorption, an aldehyde-containing solution is obtained at the tower bottom, and a tail gas is obtained at the tower top.
Aiming at the prior art, the original gas distributor is formed by welding and combining a plurality of trapezoidal stainless steel plates; under the impact of large air quantity, the sheet is easy to generate vibration, thereby causing the fatigue fracture of the material. After the breakage, the quaternary mixer is easy to damage due to bias flow of the gas, so that impurities enter the reactor to poison and inactivate the silver catalyst; and after damaging at every turn, the maintainer must get into the inside maintenance of filter, even the fire, and one of the medium is poisonous waste gas and is difficult to replace the isolation, and the maintenance space is narrow and small, has very big safety risk. Therefore, the umbrella-shaped supporting structure is welded in the gas distributor, the stainless steel plate sheets are supported one by one, the vibration of the plate sheets is reduced, the fatigue fracture of the plate sheets is avoided, and the gas bias flow factor is eliminated.
According to the present invention, preferably, the bottom of the quaternary mixer is provided with a gas distributor having an umbrella-shaped support structure, and the central axis of the gas distributor coincides with the central axis of the quaternary mixer.
As shown in fig. 2, preferably, an angle α between an extending direction of the umbrella-shaped support structure and a central axis of the gas distributor is 30-45 °. The purpose of the arrangement is to solve the problem that the precision filter core is damaged due to bias gas flow, improve the catalytic activity of the silver catalyst and prolong the service life of the silver catalyst.
Preferably, the system further comprises an alcohol filter, an oxidant filter; further preferably, the alcohol filter and the oxidant filter are each independently in communication with the quaternary mixer for filtering the alcohol and the oxidant, respectively.
In the present invention, there is a wide range of choices for the kind of the alcohol filter. Preferably, the alcohol filter is a wire mesh filter.
In the present invention, there is a wide range of choices for the type of the oxidizer filter. Preferably, the oxidizer filter is a non-metal wire mesh filter, for example, a box filter, made of glass fiber, and having a filtering precision of less than or equal to 0.1 μm.
Preferably, the system should include: the feed lines for the filtered alcohol and steam were each independently provided with a steam holding jacket.
Preferably, the system further comprises: and the feeding pipelines of the filtered oxidant and the circulating gas are respectively and independently provided with a winding type heat tracing pipe.
The invention provides a system for preparing aldehyde by oxidizing alcohol, which is shown in figure 1 and comprises: the device comprises a quaternary mixer III, a reactor IV containing a silver catalyst bed 5 and an absorption tower V which are communicated in sequence, wherein an alcohol filter I and an oxidant filter II are respectively and independently communicated with the quaternary mixer III and are respectively used for filtering the alcohol 1 and the oxidant 2; the quaternary mixer III is used for distributing and rectifying the filtered alcohol, the filtered oxidant, the steam 3 and the circulating gas 10 to obtain a mixed material 4; the reactor IV is used for contacting the mixed material 4 with the silver catalyst bed 5 and carrying out alcohol oxidation reaction, and aldehyde-containing gas 6 is obtained at the top of the reactor IV; the lower part of the absorption tower V is communicated with the upper part of the reactor IV and is used for absorbing the aldehyde-containing gas 6 and an absorbent 7, an aldehyde-containing solution 8 is obtained at the tower bottom, a tail gas 9 is obtained at the tower top, and the tail gas 9 is divided into a circulating gas 10 and a residual gas 11; and a circulating gas outlet of the absorption tower V is communicated with an inlet of the quaternary mixer III and is used for returning the circulating gas 10 to the quaternary mixer III.
Preferably, the quaternary mixer III is provided with a gas distributor having an umbrella-shaped support structure, and a central axis of the gas distributor coincides with a central axis of the quaternary mixer; further preferably, the angle α between the extending direction of the umbrella-shaped support structure and the central axis of the gas distributor is 30-45 °.
Preferably, the feed lines for filtered alcohol and steam are each independently provided with a steam insulating jacket.
Preferably, the system further comprises: and the feeding pipelines of the filtered oxidant and the circulating gas are respectively and independently provided with a winding type heat tracing pipe.
The present invention will be described in detail below by way of examples.
The total amount of silver catalyst packed in the silver catalyst bed was X/kg.
The total mesh number of the silver catalyst packed in the silver catalyst bed was Y/mesh.
The number of the silver catalyst beds including the silver catalyst bed layers is Z/piece.
The number of the metal supporting and lining nets is R/piece.
The mesh number of the metal supporting and lining net is W/mesh.
The content of the formic acid is measured by a Q/SNCC-J-05-2014-4019 method.
The concentration of the formaldehyde is measured by a Q/SNCC-J-05-2014-4019 method.
The silver catalyst is electrolytic silver and is purchased from Linyi city and noble metal catalyst Co.
Example I-1
The total amount X of the silver catalyst is 100kg, the total mesh number Y of the silver catalyst belongs to [10,60], the silver catalyst bed layer Z is 2, the number R of the copper support nets is 3, and the mesh number W of the copper support nets is 2/5/50 meshes.
The silver catalyst bed S1 comprises two silver catalyst beds which are arranged in parallel in sequence from bottom to top, silver catalysts are filled in the silver catalyst beds, the total amount of the silver catalysts filled in the silver catalyst beds is taken as a reference, the filling mass of the silver catalysts in the two silver catalyst beds is 70kg and 30kg from bottom to top, and the mesh number of the silver catalysts is 10-30 meshes and 40-60 meshes. Three copper support lining nets are arranged below the bottommost silver catalyst bed layer of the silver catalyst bed, the copper support lining nets are sequentially stacked from bottom to top, and the mesh number of the copper support lining nets is sequentially 2 meshes, 5 meshes and 50 meshes from bottom to top.
Example I-2
The total amount X of the silver catalyst is 200kg, the total mesh number Y of the silver catalyst belongs to [10,60], the silver catalyst bed layer Z is 2, the number R of the copper support nets is 3, and the mesh number W of the copper support nets is 2/5/50 meshes.
The silver catalyst bed S2 comprises two silver catalyst beds which are arranged in parallel in sequence from bottom to top, silver catalysts are filled in the silver catalyst beds, the total amount of the silver catalysts filled in the silver catalyst beds is taken as a reference, the filling mass of the silver catalysts in the two silver catalyst beds is 120kg and 80kg from bottom to top, and the mesh number of the silver catalysts is 10-30 meshes and 40-60 meshes. Three copper support lining nets are arranged below the bottommost silver catalyst bed layer of the silver catalyst bed, the copper support lining nets are sequentially stacked from bottom to top, and the mesh number of the copper support lining nets is sequentially 2 meshes, 5 meshes and 50 meshes from bottom to top.
Example I-3
The total amount X of the silver catalyst is 300kg, the total mesh number Y of the silver catalyst belongs to [10,60], the silver catalyst bed layer Z is 2, the number R of the copper support nets is 3, and the mesh number W of the copper support nets is 2/5/50 meshes.
The silver catalyst bed S3 comprises two silver catalyst bed layers which are arranged in parallel in sequence from bottom to top, silver catalysts are filled in the silver catalyst bed layers, the total amount of the silver catalysts filled in the silver catalyst bed layers is taken as a reference, the filling mass of the silver catalysts in the two silver catalyst bed layers is 200kg and 100kg from bottom to top, and the mesh number of the silver catalysts is 10-30 meshes and 40-60 meshes. The three copper support lining nets are arranged below the bottommost silver catalyst bed layer of the silver catalyst bed, the copper support lining nets are sequentially stacked and paved from bottom to top, and the mesh number of the copper support lining nets is sequentially 2 meshes, 5 meshes and 50 meshes from bottom to top.
Example I-4
The total amount X of the silver catalyst is 100kg, the total mesh number Y of the silver catalyst belongs to [10,60], the silver catalyst bed layer Z is 4, the number R of the copper support nets is 3, and the mesh number W of the copper support nets is 2/5/50 meshes.
The silver catalyst bed S4 comprises four silver catalyst beds which are arranged in parallel in sequence from bottom to top, silver catalysts are filled in the silver catalyst beds, the total amount of the silver catalysts filled in the silver catalyst beds is taken as a reference, the filling mass of the silver catalysts in the four silver catalyst beds is respectively 60kg, 20kg, 15kg and 5kg from bottom to top, and the mesh number of the silver catalysts is respectively 10-15 meshes, 15-30 meshes, 30-40 meshes and 40-60 meshes. Three copper support lining nets are arranged below the bottommost silver catalyst bed layer of the silver catalyst bed, the copper support lining nets are sequentially stacked from bottom to top, and the mesh number of the copper support lining nets is sequentially 2 meshes, 5 meshes and 50 meshes from bottom to top.
Examples I to 5
The total amount X of the silver catalyst is 200kg, the total mesh number Y of the silver catalyst belongs to [10,60], the silver catalyst bed layer Z is 4, the number R of the copper support nets is 3, and the mesh number W of the copper support nets is 2/5/50 meshes.
The silver catalyst bed S5 comprises four silver catalyst beds which are arranged in parallel in sequence from bottom to top, silver catalysts are filled in the silver catalyst beds, the total amount of the silver catalysts filled in the silver catalyst beds is taken as a reference, the filling mass of the silver catalysts in the four silver catalyst beds is respectively 100kg, 50kg, 35kg and 15kg from bottom to top, and the mesh number of the silver catalysts is respectively 10-15 meshes, 15-30 meshes, 30-40 meshes and 40-60 meshes. Three copper support lining nets are arranged below the bottommost silver catalyst bed layer of the silver catalyst bed, the copper support lining nets are sequentially stacked from bottom to top, and the mesh number of the copper support lining nets is sequentially 2 meshes, 5 meshes and 50 meshes from bottom to top.
Examples I to 6
The total amount X of the silver catalyst is 300kg, the total mesh number Y of the silver catalyst belongs to [10,60], the silver catalyst bed layer Z is 4, the number R of the copper support nets is 3, and the mesh number W of the copper support nets is 2/5/50 meshes.
The silver catalyst bed S6 comprises four silver catalyst beds which are arranged in parallel in sequence from bottom to top, silver catalysts are filled in the silver catalyst beds, the total amount of the silver catalysts filled in the silver catalyst beds is taken as a reference, the filling mass of the silver catalysts in the four silver catalyst beds is respectively 150kg, 80kg, 50kg and 20kg from bottom to top, and the mesh number of the silver catalysts is respectively 10-15 meshes, 15-30 meshes, 30-40 meshes and 40-60 meshes. The three copper support lining nets are arranged below the bottommost silver catalyst bed layer of the silver catalyst bed, the copper support lining nets are sequentially stacked and paved from bottom to top, and the mesh number of the copper support lining nets is sequentially 2 meshes, 5 meshes and 50 meshes from bottom to top.
Examples I to 7
The total amount X of the silver catalyst is 100kg, the total mesh number Y of the silver catalyst belongs to [10,60], the silver catalyst bed layer Z is 6, the number R of the copper support nets is 3, and the mesh number W of the copper support nets is 2/5/50 meshes.
The silver catalyst bed S7 comprises six silver catalyst bed layers which are arranged in parallel in sequence from bottom to top, silver catalysts are filled in the silver catalyst bed layers, the total amount of the silver catalysts filled in the silver catalyst bed is taken as a reference, the filling mass of the silver catalysts in the six silver catalyst bed layers is respectively 40kg, 20kg, 15kg, 12kg, 8kg and 5kg from bottom to top, and the mesh number of the silver catalysts is respectively 10-15 meshes, 15-20 meshes, 20-30 meshes, 30-40 meshes, 40-50 meshes and 50-60 meshes. Three copper support lining nets are arranged below the bottommost silver catalyst bed layer of the silver catalyst bed, the copper support lining nets are sequentially stacked from bottom to top, and the mesh number of the copper support lining nets is sequentially 2 meshes, 5 meshes and 50 meshes from bottom to top.
Examples I to 8
The total amount X of the silver catalyst is 200kg, the total mesh number Y of the silver catalyst belongs to [10,60], the silver catalyst bed layer Z is 6, the number R of the copper support nets is 3, and the mesh number W of the copper support nets is 2/5/50 meshes.
The silver catalyst bed S8 comprises six silver catalyst bed layers which are arranged in parallel in sequence from bottom to top, silver catalysts are filled in the silver catalyst bed layers, the total amount of the silver catalysts filled in the silver catalyst bed is taken as a reference, the filling mass of the silver catalysts in the six silver catalyst bed layers is 85kg, 40kg, 30kg, 25kg, 15kg and 5kg from bottom to top, and the mesh number of the silver catalysts is 10-15 meshes, 15-20 meshes, 20-30 meshes, 30-40 meshes, 40-50 meshes and 50-60 meshes. Three copper support lining nets are arranged below the bottommost silver catalyst bed layer of the silver catalyst bed, the copper support lining nets are sequentially stacked from bottom to top, and the mesh number of the copper support lining nets is sequentially 2 meshes, 5 meshes and 50 meshes from bottom to top.
Examples I to 9
The total amount X of the silver catalyst is 300kg, the total mesh number Y of the silver catalyst belongs to [10,60], the silver catalyst bed layer Z is 6, the number R of the copper support nets is 3, and the mesh number W of the copper support nets is 2/5/50 meshes.
The silver catalyst bed S9 comprises six silver catalyst bed layers which are arranged in parallel in sequence from bottom to top, silver catalysts are filled in the silver catalyst bed layers, the total amount of the silver catalysts filled in the silver catalyst bed is taken as a reference, the filling mass of the silver catalysts in the six silver catalyst bed layers is respectively 120kg, 90kg, 40kg, 30kg, 15kg and 5kg from bottom to top, and the mesh number of the silver catalysts is respectively 10-15 meshes, 15-20 meshes, 20-30 meshes, 30-40 meshes, 40-50 meshes and 50-60 meshes. Three copper support lining nets are arranged below the bottommost silver catalyst bed layer of the silver catalyst bed, the copper support lining nets are sequentially stacked from bottom to top, and the mesh number of the copper support lining nets is sequentially 2 meshes, 5 meshes and 50 meshes from bottom to top.
Test example 1
The silver catalyst beds (S1-S9) obtained in example I1-9 were used for the oxidation of methanol to formaldehyde.
Contacting methanol and oxygen with a silver catalyst bed, wherein the methanol and oxygen stream flows from the silver catalyst bed, each independently, from the bottom to the top, and wherein the alcohol oxidation conditions comprise: the reaction temperature is 650 ℃, the reaction pressure is 40kPa, the mass ratio of methanol to oxygen is 2, and the formaldehyde is generated through dehydrogenation and oxidation reactions.
Judgment standard of catalyst regeneration period: the reaction pressure is > 50kPa, i.e.: the reaction pressure is 40-50kPa, and the reaction running time is the regeneration period of the silver catalyst.
The test results are shown in Table 1.
TABLE 1
As can be seen from the data in Table 1, at least two silver catalyst beds are arranged in the silver catalyst bed, and the regular characteristics of the particle size and the filling quality of the silver catalyst in each silver catalyst bed are defined, so that the silver catalyst bed is used in the process of preparing aldehyde by oxidizing alcohol, the loss of the silver catalyst is effectively reduced, the activity of the silver catalyst is fully released, and the regeneration period of the silver catalyst is prolonged.
Example II-1
(1) Purifying methanol and air respectively and independently in a filter, and distributing and rectifying the obtained filtered methanol, the filtered air, steam and circulating gas in a quaternary mixer to obtain a mixed material; the quaternary mixer is provided with a gas distributor with an umbrella-shaped supporting structure, the central axis of the gas distributor is superposed with the central axis of the quaternary mixer, and the extending direction of the umbrella-shaped supporting structure and the central axis of the gas distributor form an included angle alpha of 30 degrees;
(2) contacting the mixed material with a silver catalyst bed S5 under alcohol oxidation conditions, wherein the material flow of the mixed material flows from bottom to top of the silver catalyst bed to obtain formaldehyde-containing gas;
(3) absorbing the formaldehyde-containing gas and water in an absorption tower to obtain a formaldehyde-containing solution and tail gas, dividing the tail gas into a circulating gas and a residual gas, and returning the circulating gas to the step (1);
the test results are shown in Table 2.
Examples II-2 to II-7
A formaldehyde-containing solution was obtained by following the procedure of example 1 while referring to Table 1 for the specific reaction conditions.
The test results are shown in Table 2.
Comparative example 1
According to the method of the embodiment 1, except that the tail gas is directly discharged, the other steps are the same, and the formaldehyde-containing solution is obtained.
The test results are shown in Table 2.
Comparative example 2
A formaldehyde-containing solution was obtained by following the procedure of example 1 except that the volume flow ratio of the recycle gas to the residual gas was 50: 50.
The test results are shown in Table 2.
TABLE 2
Note: 1-solid impurity content in alcohol after filtration; 2-impurity content in the filtered oxidant; 3-volume ratio of filtered alcohol, filtered oxidant, steam and recycle gas; 4-volume flow ratio of circulating gas to residual gas
As can be seen from the data in Table 2, the invention combines the filling rule characteristics of the silver catalyst bed and the purification of the reaction materials, and limits the volume flow ratio of the circulating gas and the alcohol oxidation condition, thereby being more beneficial to improving the activity of the silver catalyst and prolonging the service life of the silver catalyst.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A method for preparing aldehyde by alcohol oxidation is characterized by comprising the following steps:
(1) distributing and rectifying the filtered alcohol, the filtered oxidant and the steam to obtain a mixed material;
(2) under the condition of alcohol oxidation, enabling the mixed material to flow through a silver catalyst bed from bottom to top to carry out alcohol oxidation reaction to obtain aldehyde-containing gas;
(3) contacting the aldehyde-containing gas with an absorbent for absorption to obtain an aldehyde-containing solution and tail gas, dividing the tail gas into a circulating gas and a residual gas, and returning the circulating gas to the steam in the step (1);
wherein the volume flow ratio of the circulating gas to the residual gas is 10-40: 60-90 parts of;
wherein the silver catalyst bed comprises at least two stacked silver catalyst beds filled with silver catalyst in the following manner: according to the direction from bottom to top of the silver catalyst bed layer, the particle size and the filling quality of the silver catalyst are reduced in sequence.
2. The method of claim 1, wherein the volume ratio of the filtered alcohol, filtered oxidant, steam, and recycle gas is 1: 0.25-0.55: 0.2-1: 1-2, preferably 1: 0.36-0.44: 0.5-0.8: 1.2-1.5;
preferably, the content of solid impurities in the filtered alcohol is less than or equal to 0.01 percent by weight;
preferably, the content of impurities in the filtered oxidant is less than or equal to 0.01 percent by weight;
preferably, the number of carbon atoms of the alcohol is 1 to 5, preferably methanol and/or ethanol;
preferably, the oxidant is an oxygen-containing gas, preferably oxygen and/or air, more preferably air.
3. The process of claim 1 or 2, wherein the alcohol oxidation conditions comprise: the reaction temperature is 600-700 ℃, preferably 630-650 ℃; the reaction pressure is less than or equal to 50kPa, preferably 35-50 kPa;
preferably, the filtered alcohol, the filtered oxidant, the steam and the recycle gas are each independently subjected to a heat-preserving treatment prior to the rectification of the distribution.
4. A process according to any one of claims 1 to 3, wherein the silver catalyst has a mesh size of from 5 to 100 mesh, more preferably from 10 to 60 mesh;
preferably, the silver catalyst bed comprises 2 to 6 silver catalyst beds.
5. The process according to any one of claims 1 to 4, wherein the silver catalyst bed is further provided with a metal backing mesh, preferably a copper backing mesh;
preferably, the number of the metal supporting nets is 1-10, more preferably 1-5, and even more preferably 2-4;
preferably, the metal supporting net is arranged at intervals with the silver catalyst bed layer, and/or the metal supporting net is arranged below the bottommost silver catalyst bed layer of the silver catalyst bed; further preferably, the metal backing mesh is disposed below the bottommost silver catalyst bed layer of the silver catalyst bed;
preferably, the metal supporting and lining nets are sequentially stacked from bottom to top, and the mesh number of the metal supporting and lining nets is sequentially increased from bottom to top.
6. A system for preparing aldehyde by oxidizing alcohol is characterized by comprising: a quaternary mixer, a reactor containing a silver catalyst bed and an absorption tower which are communicated in sequence,
the quaternary mixer is used for distributing and rectifying the filtered alcohol, the filtered oxidant and the steam to obtain a mixed material;
the reactor is used for enabling the mixed material to flow through the silver catalyst bed from bottom to top to carry out alcohol oxidation reaction to obtain aldehyde-containing gas;
the absorption tower is used for contacting the aldehyde-containing gas with an absorbent for absorption to obtain an aldehyde-containing solution and tail gas, and the tail gas is divided into circulating gas and residual gas;
wherein a circulating gas outlet of the absorption tower is communicated with an inlet of the quaternary mixer and is used for returning the circulating gas to the quaternary mixer;
wherein the silver catalyst bed comprises at least two stacked silver catalyst beds filled with silver catalyst in the following manner: according to the direction from bottom to top of the silver catalyst bed layer, the particle size and the filling quality of the silver catalyst are reduced in sequence.
7. The system of claim 6, wherein the lower part of the absorption tower is communicated with the upper part of the reactor and is used for contacting the aldehyde-containing gas with an absorbent for absorption, an aldehyde-containing solution is obtained at the tower bottom, and a tail gas is obtained at the tower top;
preferably, the bottom of quaternary mixer is provided with the gas distributor of umbelliform bearing structure, and the axis of gas distributor and quaternary mixer's axis coincidence.
8. The system of claim 7, wherein the umbrella-shaped support structure extends at an angle α of 30-45 ° to the central axis of the gas distributor.
9. The system of any one of claims 6-8, wherein the system further comprises an alcohol filter, an oxidant filter;
preferably, the alcohol filter and the oxidizer filter are each independently in communication with the quaternary mixer for filtering the alcohol and the oxidizer, respectively.
10. A system according to any one of claims 6 to 9, wherein the system comprises: the feeding pipelines of the filtered alcohol and the steam are respectively and independently provided with a steam heat-preserving jacket;
preferably, the system further comprises: and the feeding pipelines of the filtered oxidant and the circulating gas are respectively and independently provided with a winding type heat tracing pipe.
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