Background technology
Dimethyl carbonate(DMC)It is the environment-friendly type Organic Chemicals that one kind meets modern " cleaning procedure " requirement, is state
One of green chemical products that border society is unanimously assert.It can not only replace phosgene, dimethyl suflfate, chloromethane and chloro-carbonic acid
Methyl esters is a kind of good green solvent and gasoline addition as being carbonylated, methylate, be esterified and the reagent of ester exchange
Agent.
Methanol and the novelty that alcoholysis of urea catalytic synthesizing dimethyl carbonate (DMC) is replacement phosgene production DMC
Process route.Alcoholysis of urea makees base stock with wide material sources, cheap urea and methanol, has raw material inexpensive easily
, technique is simple and reaction caused by ammonia the advantages that can recycling, and the anhydrous generation of course of reaction avoids first
The separation problem of alcohol-DMC- water complex systems, simplify later separation purification, reduce investment outlay, especially existing chemical fertilizer factory is opened
It is attractive to send out downstream product.
Patent WO9517369 is using Dibutyltin oxide, dimethoxide base tin, dibutyl methoxyl group NCO
Tin is reacted with methyl carbamate or urea with methanol as catalyst, while continuously steams dimethyl carbonate, such catalyst
Although higher product yield can be obtained, also can catalytic amino methyl formate decomposition.US5902894 uses height boiling point-like electron
Alms giver's oxycompound does solvent and co-catalyst, effectively inhibits the hair of the decomposition of methyl carbamate and the side reaction that methylates
It is raw.Its methyl carbamate conversion ratio is up to 98.3%, while dimethyl carbonate is selective up to 98.2%.Although organo-tin compound
With preferable catalytic effect, but their toxicity are big, price is high, homogeneous catalyst separated and recovered from product it is extremely difficult.
Patent CN1569809 proposes a kind of method by methanol and Synthesis of Dimethyl Carbonate from Urea.It is anti-in autoclave
Answer in device, at 130-180 DEG C, be as catalyst, one-step synthesis dimethyl carbonate, its yield using amine salt type ionic liquid
25-30%, selectivity are 100%.Although the catalyst effect is preferable, but still the problem of separating difficulty with product be present.
Therefore, it is that Synthesis of Dimethyl Carbonate from Urea technique is realized to develop the efficient, heterogeneous catalysis of non-environmental-pollution
Industrialized key.
The content of the invention
For equilibrium conversion in existing urea and methanol preparing dimethyl carbonate technology is low, homogeneous catalyst is not readily separated
Deficiency, the present invention provide a kind of for catalyst of urea and methanol preparing dimethyl carbonate and its preparation method and application.
The urea and methanol catalyst for preparing dimethyl carbonate of support type of the present invention, by weight content meter, contain 40% ~ 75%
Alkali-earth metal modified MFI molecular sieves, 15% ~ 30% reactive metal oxides, and 10% ~ 20% phosphorus pentoxide;Described
In alkali-earth metal modified MFI molecular sieves, 0.3% ~ 2%, the MFI molecular sieves that alkaline-earth metal accounts for MFI molecular sieves are preferably ZSM-5
Molecular sieve, described alkaline-earth metal include beryllium, magnesium, calcium, strontium, barium or radium, and preferably magnesium or calcium, described reactive metal oxides are
Zinc oxide and/or cerium oxide.
The urea of above-mentioned support type and the preparation method of methanol catalyst for preparing dimethyl carbonate, including following content:
(1)Select or prepare ZSM-5 molecular sieve;
(2)To step(1)In ZSM-5 molecular sieve be modified and prepare alkali-earth metal modified ZSM-5 molecular sieve, using leaching
Stain method, ZSM-5 is impregnated with the nitrate solution of alkaline-earth metal, then to the dry materials after dipping, roasting;
(3)Appropriate binding agent is selected, by appropriate active metal precursor solution, phosphorus pentoxide, binding agent and step
(2)Obtained material mashing, is made into suspension, then dries, extruded moulding, urea and methanol carbonic acid diformazan are obtained after roasting
Ester catalyst.
Wherein step(1)Middle ZSM-5 molecular sieve is prepared using hydrothermal synthesis method, and Si/Al mol ratios are 10 ~ 150, are preferably
20~100.Silicon source is one kind in sodium silicate salt, waterglass, Ludox or metasilicate;Silicon source is in aluminium salt or aluminate
It is a kind of;Template is one kind in n-butylamine, triethylamine, 4-propyl bromide or ethylenediamine.The desired amount of silicon source and silicon source are taken,
Solution is made with distilled water dissolving respectively, after two kinds of solution are mixed, strong stirring, while template needed for addition, use are dilute
Acid for adjusting pH value obtains white gels and stops stirring in the range of 9~11.Gel is moved into autoclave, 50~300
Crystallization 20~80 hours at a temperature of DEG C, ZSM-5 molecular sieve is obtained after products therefrom washing, filtering.
Step(2)Described in modification, using alkaline-earth metal nitrate solution impregnate ZSM-5 molecular sieve, alkaline-earth metal
Nitrate solution be magnesium nitrate or calcium nitrate solution, preferably magnesium nitrate solution, dip time is 1~15 hour, preferably 2~
10 hours;Dried at a temperature of 70~350 DEG C, and in 250~650 DEG C of roasting temperatures 2~20 hours, preferably 80~300 DEG C of temperature
The lower drying of degree, and in 300~600 DEG C of roasting temperatures 2~10 hours.Ammonium exchange processing can also be entered before modification, obtain hydrogen
Type ZSM-5 molecular sieve.
Step(3)The addition of described phosphorus pentoxide is the 10% ~ 17% of catalyst quality.Phosphorus pentoxide can have
Ammonia caused by the absorbing reaction of effect, reaction balance is promoted to be carried out to positive direction, so as to improve the yield of dimethyl carbonate.
Step(3)Described adhesive is selected from Ludox or Al2O3In one kind, preferably Al2O3.Binder dosage is to urge
The 20%~40% of the 10%~50% of agent quality, preferably catalyst quality.
Step(3)Described active metal presoma is one or both of zinc salt or cerium salt, and wherein zinc salt is nitric acid
Zinc, zinc acetate or zinc chloride, cerium salt are cerous nitrate, cerous nitrate or cerous chlorate.(3)The amount of described active metal presoma
For the 15%~35% of modified ZSM-5.
Step(3)Contain also appropriate 1 in described active metal precursor solution, 3,5- trimesic acids, content is
The 5% ~ 25% of active metal forerunner's weight, preferably 10% ~ 20%.The introducing of 1,3,5- trimesic acids is the same as alkali-earth metal modified
Molecular sieve interaction afterwards significantly improves the yield of dimethyl carbonate.
Step(3)Middle article shaped obtains urea and methanol carbonic acid diformazan for 2~8 hours through 300~550 DEG C of roasting temperatures
Ester catalyst.
Application of the above-mentioned loaded catalyst in urea and methanol preparing dimethyl carbonate, using urea and methanol as raw material,
Urea is 1 with methanol molar ratio:5~1:20, catalyst amount is the 7%~20% of reactant gross mass, reaction temperature 90-
210 DEG C, it is preferred to use two sections of temperature reactions, at one section of 100~150 DEG C of reaction temperature, react 2~6h, second-stage reaction temperature 170
At~200 DEG C, 2~8h is reacted.
The urea and methanol catalyst for preparing dimethyl carbonate of the present invention, solves urea and methanol-fueled CLC dimethyl carbonate skill
The problems such as equilibrium conversion is low in art, homogeneous catalyst is difficult to separation and recovery, the method for preparing catalyst is simple, is easily recycled point
From improving product quality, stability is good.
Embodiment
The functions and effects of the present invention are further illustrated with reference to embodiment.
Example 1
(1)Prepare ZSM-5 molecular sieve.The aqueous solution 100ml containing 90 grams of waterglass is prepared, adds contain 13 grams of sulphur thereto
The aqueous solution 30ml of sour aluminium, strong stirring.16 grams of 4-propyl bromides are added simultaneously as template, and pH value is adjusted with dilute sulfuric acid
For 10.Continue to stir, until obtaining jelly, gained jelly is moved into autoclave, 40 hours are incubated at 140 DEG C.It is brilliant
After change terminates, products therefrom washing obtains the ZSM-5 molecular sieve that silicon/aluminum ratio is 50 after filtering, ammonium obtains Hydrogen after exchanging
ZSM-5 molecular sieve.
(2)Hydrogen ZSM-5 is modified, using Mg (NO3)2The aqueous solution impregnates to ZSM-5 to be modified.Take 8gMg (NO3)2
The 60ml aqueous solution is made into, and adds 65 grams of ZSM-5 thereto, is stirred, dipping is after 6 hours, drying at room temperature, 100 DEG C of drying,
The Mg modified ZSM-5s of Hydrogen are obtained after 500 DEG C of roastings, Mg contents are 0.5wt%.
(3)12g zinc nitrates and 2.4g phosphorus pentoxides are dissolved in 40ml distilled water, using Al2O3For adhesive, by Mg
Modified ZSM-5 50g, adhesive 20g and zinc nitrate solution mixing are made into suspension, extruded moulding after drying, at 500 DEG C
Roasting 6h obtains catalyst.
Evaluating catalyst is carried out using autoclave reactor, using urea and methanol as raw material, wherein urea 20g, methanol
70g, 10 grams of catalyst quality, one section of 120 DEG C of reaction temperature, 4h is reacted, 190 DEG C of second-stage reaction temperature, reacts 4h, carbonic acid diformazan
Ester yield reaches 20.5%.
Example 2
(1)Prepare ZSM-5 molecular sieve.The aqueous solution 120ml containing 95 grams of waterglass is prepared, adds contain 12 grams of sulphur thereto
The aqueous solution 30ml of sour aluminium, strong stirring.18 grams of 4-propyl bromides are added simultaneously as template, and pH value is adjusted with dilute sulfuric acid
For 11.Continue to stir, until obtaining jelly, gained jelly is moved into autoclave, 30 hours are incubated at 150 DEG C.It is brilliant
After change terminates, products therefrom washing obtains the ZSM-5 molecular sieve that silicon/aluminum ratio is 80 after filtering, ammonium obtains Hydrogen after exchanging
ZSM-5 molecular sieve.
(2)Hydrogen ZSM-5 is modified, using Mg (NO3)2The aqueous solution impregnates to ZSM-5 to be modified.Take 20gMg (NO3)2
The 110ml aqueous solution is made into, and adds 85 grams of ZSM-5 thereto, is stirred, dipping is after 6 hours, drying at room temperature, 130 DEG C of bakings
It is dry, the Mg modified ZSM-5s of Hydrogen are obtained after 500 DEG C of roastings, Mg contents are 1.3wt%.
(3)20g zinc nitrates and 2.4g phosphorus pentoxides are dissolved in 40ml distilled water, using Al2O3For adhesive, by Mg
Modified ZSM-5 86g, adhesive 35g and zinc nitrate solution mixing are made into suspension, extruded moulding after drying, at 400 DEG C
Roasting 5h obtains catalyst.
Evaluating catalyst is carried out using autoclave reactor, using urea and methanol as raw material, wherein urea 15g, methanol
100g, catalyst quality 23g, one section of 120 DEG C of reaction temperature, 4h is reacted, 180 DEG C of second-stage reaction temperature, reacts 5h, carbonic acid diformazan
Ester yield reaches 23.4%.
Example 3
(1)Prepare ZSM-5 molecular sieve.The aqueous solution 90ml containing 75 grams of waterglass is prepared, adds contain 23 grams of sulphur thereto
The aqueous solution 50ml of sour aluminium, strong stirring.16 grams of 4-propyl bromides are added simultaneously as template, and pH value is adjusted with dilute sulfuric acid
For 11.Continue to stir, until obtaining jelly, gained jelly is moved into autoclave, 25 hours are incubated at 150 DEG C.It is brilliant
After change terminates, products therefrom washing obtains the ZSM-5 molecular sieve that silicon/aluminum ratio is 30 after filtering, ammonium obtains Hydrogen after exchanging
ZSM-5 molecular sieve.
(2)Hydrogen ZSM-5 is modified, using Mg (NO3)2The aqueous solution impregnates to ZSM-5 to be modified.Take 13gMg (NO3)2
The 90ml aqueous solution is made into, and adds 65 grams of ZSM-5 thereto, is stirred, dipping is after 5 hours, drying at room temperature, 130 DEG C of drying,
The Mg modified ZSM-5s of Hydrogen are obtained after 450 DEG C of roastings, Mg contents are 1.0wt%.
(3)18g cerous nitrates and 2.4g phosphorus pentoxides are dissolved in 40ml distilled water, using Al2O3, will for adhesive
Modified Mg ZSM-5 70g, adhesive 42g and cerium nitrate solution mixing are made into suspension, extruded moulding after drying, nitrogen
Roasting 4h at lower 450 DEG C is protected to obtain catalyst.
Evaluating catalyst is carried out using autoclave reactor, using urea and methanol as raw material, wherein urea 12g, methanol
130g, catalyst quality 12g, one section of 130 DEG C of reaction temperature, 5h is reacted, 180 DEG C of second-stage reaction temperature, reacts 5h, carbonic acid diformazan
Ester yield reaches 24.7%.
Example 4
(1)Prepare ZSM-5 molecular sieve.The aqueous solution 80ml containing 65 grams of waterglass is prepared, adds contain 8 grams of sulfuric acid thereto
The aqueous solution 20ml of aluminium, strong stirring.10 grams of 4-propyl bromides are added simultaneously as template, are with dilute sulfuric acid regulation pH value
11.Continue to stir, until obtaining jelly, gained jelly is moved into autoclave, 20 hours are incubated at 180 DEG C.Crystallization
After end, products therefrom washing obtains the ZSM-5 molecular sieve that silicon/aluminum ratio is 70 after filtering, ammonium obtains the ZSM- of Hydrogen after exchanging
5 molecular sieves.
(2)Hydrogen ZSM-5 is modified, using Mg (NO3)2The aqueous solution impregnates to ZSM-5 to be modified.Take 21gMg (NO3)2
The 90ml aqueous solution is made into, and adds 68 grams of ZSM-5 thereto, is stirred, dipping is after 5 hours, drying at room temperature, 150 DEG C of drying,
The Mg modified ZSM-5s of Hydrogen are obtained after 500 DEG C of roastings, Mg contents are 1.8wt%.
(3)By 22g zinc nitrates, the equal benzene of 1.8g1,3,5-Tricarboxylic acidIt is dissolved in 1.8g phosphorus pentoxides in 45ml distilled water,
Using Al2O3For adhesive, ZSM-5 75g modified Mg, adhesive 53g and zinc nitrate solution are mixed and are made into suspension, done
Extruded moulding after dry, roasting 7h obtains catalyst at 600 DEG C.
Evaluating catalyst is carried out using autoclave reactor, using urea and methanol as raw material, wherein urea 12g, methanol
108g, 19 grams of catalyst quality, one section of 140 DEG C of reaction temperature, 5h is reacted, 160 DEG C of second-stage reaction temperature, reacts 6h, carbonic acid two
Methyl esters yield reaches 26.3%.
Example 5
(1)Prepare ZSM-5 molecular sieve.The aqueous solution 110ml containing 90 grams of waterglass is prepared, adds contain 10 grams of sulphur thereto
The aqueous solution 25ml of sour aluminium, strong stirring.13 grams of 4-propyl bromides are added simultaneously as template, and pH value is adjusted with dilute sulfuric acid
For 10.Continue to stir, until obtaining jelly, gained jelly is moved into autoclave, 35 hours are incubated at 150 DEG C.It is brilliant
After change terminates, products therefrom washing obtains the ZSM-5 molecular sieve that silicon/aluminum ratio is 90 after filtering, ammonium obtains Hydrogen after exchanging
ZSM-5 molecular sieve.
(2)Hydrogen ZSM-5 is modified, using Mg (NO3)2The aqueous solution impregnates to ZSM-5 to be modified.Take 15gMg (NO3)2
The 80ml aqueous solution is made into, and adds 60 grams of ZSM-5 thereto, is stirred, dipping is after 6 hours, drying at room temperature, 130 DEG C of drying,
The Mg modified ZSM-5s of Hydrogen are obtained after 500 DEG C of roastings, Mg contents are 1.5wt%.
(3)15g cerous nitrates, 2.5g1,3,5- trimesic acids and 1.7g phosphorus pentoxides are dissolved in 35ml distilled water
In, using Al2O3For adhesive, ZSM-5 60g modified Mg, adhesive 45g and cerium nitrate solution are mixed and are made into suspension
Liquid, extruded moulding after drying, the lower 550 DEG C of roastings 5h of nitrogen protection obtain catalyst.
Evaluating catalyst is carried out using autoclave reactor, using urea and methanol as raw material, wherein urea 18g, methanol
130g, 20 grams of catalyst quality, one section of 110 DEG C of reaction temperature, 6h is reacted, 170 DEG C of second-stage reaction temperature, reacts 5h, carbonic acid two
Methyl esters yield reaches 29.6%.