A kind of complex type molecular sieve catalysis and preparation method thereof and the application in preparation acrylic acid
Technical field
The invention belongs to Preparation of Catalyst and chemical technology field, particularly a kind of complex type molecular sieve catalysis and preparation method thereof and the application in preparation acrylic acid.
Background technology
Acrylic acid is the important organic synthesis monomer of a class, is widely used in industries such as chemical fibre, weaving, adhesive, coating, plastics, process hides.Over nearly 10 years, the market of China's acrylic acid and ester thereof is built, weaving, and the pulling in fields such as packing and hygienic material has had high speed development, and the domestic degree of self-sufficiency is downward trend year by year, therefore acrylic acid imbalance between supply and demand will be compared anxiety.Traditional acrylic acid industry is based upon on the petrochemical industry basis fully, and these routes all are to be the raw material acrylic acid synthesizing with petroleum chemicals, as early stage cyanoethanol method (German Rohm ﹠amp; Hass company, 1937), improved Reppe method (Rohm ﹠amp; Hass company, 1952), propylene cyanogen Hydrolyze method (French Ugine Kuhlmann company, 1955), oxidation of propylene (UCC company, 1969), Japanese catalyst method, Mitsubishi oiling method, BASF method (the later stage sixties).But the difficult problem that these class methods face at present mainly is the shortage of fossil resource, the raising of production cost and to the pollution of environment.Therefore, need find a kind of new synthetic route to replace the production method of petroleum base route.
Biomass resource has now been obtained great successes at present, and as the lactic acid industry of fermenting and producing, having formed with starch is the submerged fermentation of raw material, with low cost, and reaches considerable scale.Also might use more cheap newborn string hydrolysate etc. to be fermenting raw materials from now in a large number, therefore, the hardware and software platform compound that lactic acid can be used as a kind of cheapness prepares high value-added product.Just had with lactic acid in early days is the acrylic acid report of feedstock production: 1958, Holmen etc. (US2859240) studied the direct catalytic dehydration of lactic acid, found that the most effective catalyst is the CaSO4/Na2SO4 composite catalyst, can realize 68% theoretical yield; Paparizos etc. (US4786756) adopt similar method, are that catalyst conversion lactic acid is acrylic acid with AlPO4, and last productive rate is 43%.But the action in their early stage all is to be catalyst with metal oxide etc., and productive rate is lower, also further report not.
HZSM-5 and NaY zeolite molecular sieve all belong to a class novel crystallization silicate zeolite, because of it has unique pore passage structure, and surface acidity, catalytic performance and good heat endurance, and in chemical industry, find broad application.Now people can be to the Acidity of Aikalinity of porous materials such as zeolite molecular sieve, hole size and select the shape effect and systematically regulate, and this makes them bring into play more and more important effect.Zeolite molecular sieve can catalytic hydrocarbon cracking, alkylation, hydrocracking, isomerization, hydrogenation dehydrogenation, dehydration, alkylation, select that shape is reformed and many reactions [Xu Rurens such as MTG, Pang Wenqin etc. molecular sieve and porous material chemistry. Beijing: Science Press, 2004].Wherein, zeolite molecular sieve be proved can the many alcohols of efficient catalytic dehydration [high grow etc. zeolite catalysis and isolation technics. Beijing: Sinopec publishing house, 1999], yet be converted in acrylic acid research, do not had report that it is studied as catalyst carrier at acid by dehydrating lactic.
Summary of the invention
The purpose of this invention is to provide that a kind of low cost, preparation method are simple, the composite catalyst of excellent catalytic effect.
Another object of the present invention provides above-mentioned Preparation of catalysts method.
A further object of the invention provides the application of above-mentioned catalyst in crylic acid preparation by lactic acid dehydration.
The objective of the invention is to realize by following technical measures:
A kind of complex type molecular sieve catalysis, this catalyst contains following components in weight percentage:
HZSM-5 molecular sieve 0.1~93%
NaY molecular sieve 6~99.8%
K 0.001~1.0%。
Described catalyst, wherein the silica alumina ratio of HZSM-5 molecular sieve is 25-150; The silica alumina ratio of NaY molecular sieve is 2.8-10.
This composite catalyst be a kind of be the solid acid catalyst of main component with NaY molecular sieve and HZSM-5 molecular sieve.
Described Preparation of catalysts method, this preparation method may further comprise the steps: get HZSM-5 molecular sieve and NaY molecular sieve by the proportion relation of above-mentioned catalytic component, add and contain K
+Solution, mix, filter, filter cake promptly gets required catalyst after roasting.The catalyst that obtains after the roasting further compressing tablet, grinding, screening is made required form and size.
Described Preparation of catalysts method, concrete processing step comprises:
A. respectively HZSM-5, NaY are removed the impurity of its absorption at 150-800 ℃ of roasting 0.5-4h, pulverize, standby;
B. place and contain K by learn from else's experience HZSM-5 that step a handles and NaY of the proportion relation of catalytic component
+In the solution, after 30-100 ℃ is stirred 0.5-8h down, filter, get filter cake;
C. get filter cake at 150-800 ℃ of roasting 3-20h, promptly obtain the compound K/HZSM-5/NaY molecular sieve catalyst of powdery, further make the compound K/HZSM-5/NaY molecular sieve catalyst of 20-100 purpose by compressing tablet, grinding, screening.
Described preparation method wherein contains K
+K in the solution
+Concentration is 0.01-5wt%.
The application of above-mentioned catalyst in crylic acid preparation by lactic acid dehydration.
Described application is material acid solution to be injected fixed bed reactors with inert gas (must lead to inert gas when leading to lactic acid solution.Can feed the inert gas appropriate time earlier, under the situation that keeps ventilation, feed lactic acid solution then), after the preheating vaporization, react by the catalytic bed that contains described catalyst, reaction temperature is being 280-450 ℃, reaction 0.5-5h, gas-liquid separation is realized in product cooling back, collects the acrylic acid in the product liquid phase.
Described application, wherein material acid is the fermentation lactic acid by the fermentation gained, or the lactic acid of chemical synthesis.The initial concentration of material acid is 20-85wt%.
Described application, wherein fermentation lactic acid is to be that raw material is made by fermentation with the recyclability biomass resource; These recyclability biomass resources are that starch, corn, molasses, potato are done, cassava or stalk.
Beneficial effect of the present invention:
Conversion ratio by the crylic acid preparation by lactic acid dehydration reaction under catalyst action can reach 99%, and selectivity can reach more than 70%.Lactic acid can be chemical synthesis, is that fermenting raw materials forms with reproducible biomass resource also.If with the fermentation lactic acid is raw material, there are not the dependence to the petrochemical industry resource in then acrylic acid preparation and production.In addition, it is few to have an accessory substance with the acrylic acid process of acid by dehydrating lactic prepared in reaction of this catalyst, and equipment is simple, and technology is easy to advantages such as control.
Operating process of the present invention is simple, be easy to control, reaction condition gentleness, cost are lower, has the favorable industrial application prospect.
The specific embodiment
The present invention is further described by the following examples, but content not thereby limiting the invention.
General explanation:
The catalyst performance test is carried out on homemade fixed bed reactors among the embodiment.Pipe is the quartz ampoule of the long 300mm wall thickness of internal diameter 8mm 1mm in the self-control fixed bed reactors.Catalyst layer is positioned at the position placed in the middle of quartz ampoule.Crystal reaction tube places the aluminum heating jacket, and heating jacket heats by electrically heated rod, and thermocouple is positioned at the heating jacket layer near inner wall section.The duty of heating rod is carried out real-time monitoring according to the feedback information of thermocouple.The reactor feed mouth is introduced gas and liquid respectively by three-way connection.What the injection port of gas connected is gas bomb, middle gas flow with mass flow controller control nitrogen.What the liquid injection port connected is the lactic acid solution raw material, middle flow with constant flow pump control lactic acid solution.Reactor exit is drawn product by the stainless steel pipeline, and the stainless steel pipeline feeds receiving flask through condensate tank(trap).Adopt the similar commercially available fixed bed reactors of structure to can be used in catalyst performance test among the present invention too.
Molecular sieve is all removed the impurity of its absorption at 150-800 ℃ of roasting 0.5-4h among the embodiment, pulverizes, and is standby.Recyclability biomass resources such as fermentation lactic acid is that starch, corn, molasses, potato are done, cassava or stalk are that raw material is made by fermentation, and the method for fermentation is a technology known to a person of ordinary skill in the art.Described fermentation lactic acid also can be bought by market and obtain.
Embodiment 1
0.2g KCl is dissolved in the 200ml water, again with 12g NaY molecular sieve (silica alumina ratio is 5), 8g HZSM-5 molecular sieve (silica alumina ratio is 50) mixes, and in 80 ℃ of stirring 4h, is cooled to 40 ℃ and stops to stir, after filter cake changes 120 ℃ of oven dryings over to after filtering, put into 550 ℃ of roasting 4h of Muffle furnace, cooling cooling, compression molding, grind to the 50-100 order and sieve, compound K/HZSM-5/NaY molecular sieve catalyst.
The compound K/HZSM-5/NaY molecular sieve catalyst of getting the 1.5g gained is packed into and is made the constant temperature zone of fixed bed reactors by oneself, and remainder is filled with quartz sand.At N
2Under the gas velocity 20ml/min catalytic bed is warmed up to 350 ℃, be the flow velocity injected system of the fermentation lactic acid solution of 34wt% then with initial concentration with 5ml/h, react by catalytic bed gasification back, and product is through the refrigerated separation gas-liquid, reacts after 1 hour liquid sampling and analyze.Composite catalyst K/HZSM-5/NaY, acid by dehydrating lactic conversion ratio 95.7%, the acrylic acid selectivity is 54.8%.Under the same reaction conditions, the former powder catalysis of HZSM-5 acid by dehydrating lactic conversion ratio is 99.3%, and the acrylic acid selectivity is 1.27%; The conversion ratio of the former powder catalysis of NaY acid by dehydrating lactic is 77.3%, and the acrylic acid selectivity is 57.6%; As seen, the resultant effect of composite catalyst K/HZSM-5/NaY will obviously be better than former powder.
Embodiment 2
With the 10g silica alumina ratio is that 50 HZSM-5 and 10g silica alumina ratio are that 3.0 NaY molecular sieve is a base stock, places 300ml K
+Concentration is the KNO of 0.2wt%
3In the solution, 80 ℃ are stirred 1h, filter, and get filter cake 550 ℃ of roasting 4h in Muffle furnace, and compressing tablet, grinding, screening obtain the compound K/HZSM-5/NaY catalyst of 50-100 order moulding.
In homemade fixed bed reactors, add the compound K/HZSM-5/NaY catalyst 2.0g of gained, be 350 ℃ in temperature, the liquid air speed is 0.4h
-1Down, be that the fermentation lactic acid of 34wt% carries out the dehydration test to initial concentration, reaction 3h, the lactic acid conversion ratio is 99.34%, the acrylic acid selectivity can reach 61.55%.
Embodiment 3
With silica alumina ratio is that 25 HZSM-5 molecular sieve 6.0g and silica alumina ratio are that 3.8 NaY molecular sieve 14.0g places 300ml K
+Concentration is in the KCl solution of 0.1wt%, and 80 ℃ are stirred 4h, filter, and get filter cake 550 ℃ of roasting 4h in Muffle furnace, and compressing tablet, grinding, screening obtain the compound K/HZSM-5/NaY catalyst of 30-50 order moulding.
In the fixed bed reactors of development voluntarily, add the compound K/HZSM-5/NaY catalyst 2.0g of gained, be 375 ℃ in temperature, the liquid air speed is 0.4h
-1Down, be that the fermentation lactic acid solution of 34wt% carries out dehydration experiment to initial concentration, reaction 2h, the lactic acid conversion ratio is 99.56%, the acrylic acid selectivity can reach 65.5%.
Embodiment 4
With silica alumina ratio is that 25 HZSM-5 molecular sieve 6.0g and silica alumina ratio are that 3.8 NaY molecular sieve 14.0g places and contains 200ml K
+Concentration is in the KCl solution of 0.2wt%, and 90 ℃ are stirred 4h, filter, and get filter cake 550 ℃ of roasting 4h in Muffle furnace, and compressing tablet, grinding, screening obtain the compound K/HZSM-5/NaY catalyst of 20-50 order moulding.
In the fixed bed reactors of development voluntarily, add this compound K/HZSM-5/NaY catalyst of 2.0g, be 350 ℃ in temperature, the liquid air speed is 0.4h
-1Down, nitrogen flow rate is 50ml/min, and the 50wt% fermentation lactic acid is carried out dehydration experiment.This composite catalyst is moved 24h continuously, and catalyst activity is constant substantially, shows this catalyst good stable.
Embodiment 5
With silica alumina ratio is that 25 HZSM-5 molecular sieve 6.0g and silica alumina ratio are that 3.8 NaY molecular sieve 14.0g places 250ml K
+Concentration is 0.3wt%KNO
3Solution in, 80 ℃ are stirred 4h, filter, and get filter cake 550 ℃ of roasting 4h in Muffle furnace, compressing tablet, grinding, screening obtain the compound K/HZSM-5/NaY catalyst of 30-50 order moulding.
As catalyst, in the self-control fixed bed reactors, carry out the acid by dehydrating lactic reaction with this compound K/HZSM-5/NaY molecular sieve.Add the compound K/HZSM-5/NaY molecular sieve catalyst of 2.5g in fixed bed reactors, the initial concentration of chemical synthesis lactic acid is 40wt%, and reaction temperature is 375 ℃, and the liquid air speed is 0.4h
-1, N
2Flow velocity be 50ml/min, ask 1h during reaction, the lactic acid conversion ratio is 99.8%, the acrylic acid selectivity can reach 70.9%.