A kind of method of acetylene selective catalytic hydrogenation system ethene
Technical field
The present invention relates to the method for acetylene selective catalytic hydrogenation system ethene,, also above-mentioned catalyst is used for the method that selective catalytic hydrogenation is removed the ethene a little acetylene with molybdenum phosphide catalyst.
Background technology
The process of industrial preparation ethene relates generally to hydrocarbon cracking system ethene and acetylene selective catalytic hydrogenation system ethene, still contains the acetylene of trace in the ethylene gas that these processes make.The existence of trace acetylene can make ethylene rolymerization catalyst poison and inactivation makes the polymer performance variation that finally makes, and therefore must remove by wherein micro-acetylene before ethylene raw material gas carries out polymerisation.From present result of study, by selective catalytic hydrogenation acetylene optionally being hydroconverted into ethene is the most feasible and valuable method.Yet the acetylene hydrogenation reaction belongs to cascade reaction (C
2H
2→ C
2H
4→ C
2H
6), the ethene that generates in the hydrogenation process very easily further hydrogenation generates ethane, thereby cause ethylene selectivity sharply to reduce, remove the Pd catalyst of ability also so (US 20090326288 even have high trace acetylene along with the increase of conversion of alkyne; US 20040074220; CN 1317367; CN 1657513; CN 1151908; A.Sarkany, A.Beck, L.Guczi.Appl.Catal.A, 2003,253:283; W.Huang, J.R.McCormick, J.G.Chen.J.Catal., 2007,246:40).In at present numerous research, mainly still concentrate on research, and Ag, Co, Cu, Cr, alkali metal, metal oxide and lead acetate are the known auxiliary agent that can improve performance of Pd catalyst (US 7247760B2 to the Pd catalyst system; W.Huang, W.Pyrz, J.G.Chen.Appl.Catal.A, 2007,333:254; J.H.Kang, E.W.Shin, S.H.Moon.Catal.Today, 2000,63:183; Y.Jin, A.K.Datye, J.Blackson, J.Catal., 2001,203:2001).From present achievement in research, high catalyst cost is to limit one of further key factor of using of this technology, and is still rare to the research of non-precious metal catalyst.Therefore, how to reduce catalyst cost, raising selection of catalysts and activity is the emphasis of this research always, and it is also imperative to develop a kind of catalyst inexpensive, that have high activity and high selectivity.For this reason, the research worker is still trying to explore the new catalyst system that selective catalytic hydrogenation removes trace acetylene in the ethene both at home and abroad.
Transition metal phosphide is an another catalyst material with good hydrogenation performance after nitride and carbide, in catalytic hydrogenation reaction, has good hydrogen-involved reaction performance, in the research of the hydrodenitrogeneration of fuel oil and desulfurization, obtained result (D.C.Phillips preferably in recent years, S.J.Sawhill, R.Self, M.E.Bussell.J.Catal., 2002,207:266; F.Sun, Z.Jiang, C.Li.J.Catal., 2004,228:298).It is the research that catalyst is used for acetonitrile gas phase hydrogenation system ethylamine compounds that this seminar has carried out with the phosphatization molybdenum first, and has obtained a series of significant achievements.The application that molybdenum phosphide catalyst is used for other hydrogenation reaction system seldom, therefore further deeply develop application as novel hydrogenation catalyst phosphatization molybdenum, no matter this is to the development of molybdenum phosphide catalyst or the exploitation of hydrogenation catalyst reaction, all have important academic significance and using value, the phosphatization molybdenum is used for the research that the acetylene selective catalytic hydrogenation prepares ethene yet there are no report.
Summary of the invention
The object of the present invention is to provide a kind of method of using molybdenum phosphide catalyst to prepare ethene at the acetylene selective catalytic hydrogenation; Method for preparing catalyst is simple, low, the active height of acetylene hydrogenation of catalyst cost, still keeps higher ethylene selectivity under high conversion of alkyne situation.
For achieving the above object, technical solution of the present invention realizes by following steps:
A kind of method of acetylene selective catalytic hydrogenation system ethene is a catalyst with the phosphatization molybdenum.
Molybdenum phosphorus mol ratio 0.9-1.1 in the described phosphatization molybdenum.
Reaction pressure is a normal pressure, and reaction temperature is 200~240 ℃, H
2/ C
2H
2Mol ratio=4~8, air speed are 33,000~38,000h
-1
Described molybdenum phosphide catalyst is a pure phase phosphatization molybdenum or with SiO
2Support type phosphatization molybdenum for carrier.
Described SiO
2In the support type molybdenum phosphide catalyst, the weight percentage of phosphatization molybdenum is 20~35wt%.
Pure phase MoP prepares by the high-temperature hydrogen temperature programmed reduction, and support type phosphatization molybdenum is that active component Mo, P raw material are loaded on SiO by wet infusion process
2On the carrier, make by the high-temperature hydrogen temperature programmed reduction again.
In the technique scheme, the molar ratio example of molybdenum, phosphorus is 0.90~1.10 in the precursor of pure phase MoP.In normal pressure, reaction temperature is 200~240 ℃, H
2/ C
2H
2=4~8 o'clock, reach at conversion of alkyne under 99.5% the situation, selectivity of ethylene still keeps more than 76%.
The molybdenum of support type MoP catalyst, phosphorus ingredient proportion are 1, and the MoP load capacity is 20~35wt%.In normal pressure, reaction temperature is 200~240 ℃, H
2/ C
2H
2, reach the ethylene selectivity that still can keep under 99.8% the situation more than 70% at conversion of alkyne at=4~8 o'clock.
The used raw material of catalyst composition of the present invention is: molybdenum element is selected from ammonium molybdate or molybdenum trioxide.P elements is selected from ammonium phosphate salt.
Preparation of catalysts method involved in the present invention is: mix after at first the molybdate compound of certain mol proportion and ammonium phosphate salt being dissolved in distilled water, with the liquid evaporate to dryness, 120 ℃ of dryings 10~24 hours were in 450~650 ℃ of roastings 2~8 hours.Then, the phosphatization molybdenum presoma after the roasting is carried out the multi-stage procedure heating reduction under nitrogen atmosphere.Reducing condition is: with heating rate is that 2~10 ℃/min rises to 250~400 ℃ from room temperature, is 0.5~2 ℃/min with heating rate, rises to 550~900 ℃ from 250~400 ℃, and outlet temperature insulation 2~4 hours.After reaction finishes, under the room temperature, be that 0.5~1.5% passivating gas carries out passivation to product with oxygen concentration, obtain pure phase MoP catalyst.
The preparation process of support type phosphatization molybdenum and pure phase phosphatization molybdenum is similar, and different is, is after 1 molybdate compound and ammonium phosphate salt dissolving mix, to be immersed in SiO with mol ratio
2On the carrier.
Compare with known technology, the present invention has the following advantages:
This method is used for acetylene selective catalytic hydrogenation system ethene with base metal MoP catalyst, high reaction velocity (36,000h
-1) time, for MoP and MoP/SiO
2Catalyst acetylene hydrogenation conversion ratio and hydrogenation products ethylene selectivity can reach respectively more than 99% and 70%.Compare (as palladium catalyst) with traditional noble metal catalyst, molybdenum phosphide catalyst has preparation method simple, cheap and catalytic hydrogenation activity and selectivity advantages of higher.
For pure phase phosphatization molybdenum, high reaction velocity (36,000h
-1), in the wide range of reaction temperature (200~240 ℃), shown good acetylene catalytic hydrogenation activity, under high conversion ratio, still can keep high ethylene selectivity.For with SiO
2Be the support type molybdenum phosphide catalyst of carrier, have higher acetylene catalytic hydrogenation activity and product selectivity of ethylene, can be at lower H
2/ C
2H
2Obtain high catalytic hydrogenation activity and selectivity under the mol ratio.Compare (as palladium catalyst) with traditional noble metal catalyst, molybdenum phosphide catalyst has preparation method simple, cheap and catalytic hydrogenation activity and selectivity advantages of higher.
Under described operating condition, use described catalyst can obtain to be higher than 99.5% conversion of alkyne and be higher than 70% ethylene selectivity.
The specific embodiment
The present invention carries out selective catalytic hydrogenation with above-mentioned catalyst, and key step is: with a certain amount of MoP or MoP/SiO
2Catalyst is packed in the fixed bed reactors, in the High Purity Hydrogen air-flow of 100mL/min under 600 ℃ with catalyst preliminary treatment 1h; After preliminary treatment finishes, naturally cool to the reaction temperature of setting, according to certain H
2/ C
2H
2Than feeding reactor feed gas.At normal pressure, 200~240 ℃, H
2/ C
2H
2=4~8, air speed is 33,000~38,000h
-1Under investigate the acetylene Catalytic Hydrogenation Properties.
In order to further specify the present invention, enumerate following examples, but it does not limit the defined invention scope of each accessory claim.
Embodiment 1
With molybdenum phosphorus mol ratio is that the 1 pure phase phosphatization molybdenum that makes is a catalyst, and acetylene hydrogenation is reflected in the micro fixed-bed reactor and carries out.Unstripped gas is formed: the Ar gaseous mixture of the acetylene of 1.0vol% and 99.0vol%, reaction condition is: 0.10g catalyst, 200 ℃ of temperature, normal pressure, H
2/ C
2H
2=8, feed gas flow rates 60mL/min, air speed 36,000h
-1Product analysis adopts Agilent gas-chromatography, hydrogen flame detector.
Embodiment 2
With embodiment 1, be that 0.9 pure phase phosphatization molybdenum is a catalyst with molybdenum phosphorus mol ratio, reaction result is listed in table 1.
Embodiment 3
With embodiment 1, be that 0.95 pure phase phosphatization molybdenum is a catalyst with molybdenum phosphorus mol ratio, reaction result is listed in table 1.
Embodiment 4
With embodiment 1, be that 1.05 pure phase phosphatization molybdenum is a catalyst with molybdenum phosphorus mol ratio, reaction result is listed in table 1.
Embodiment 5
With embodiment 1, be that 1.10 pure phase phosphatization molybdenum is a catalyst with molybdenum phosphorus mol ratio, reaction result is listed in table 1.
Embodiment 6
With embodiment 1, be 200 ℃ in reaction temperature and investigate the acetylene hydrogenation activity down that reaction result is listed in table 1.
Embodiment 7
With embodiment 1, be 220 ℃ in reaction temperature and investigate the acetylene hydrogenation activity down that reaction result is listed in table 1.
Embodiment 8
With embodiment 1, be 240 ℃ in reaction temperature and investigate the acetylene hydrogenation activity down that reaction result is listed in table 1.
Embodiment 9
With embodiment 7, at H
2/ C
2H
2Investigate the acetylene hydrogenation activity=8 times, reaction result is listed in table 1.
Embodiment 10
With embodiment 7, at H
2/ C
2H
2Investigate the acetylene hydrogenation activity=6 times, reaction result is listed in table 1.
Embodiment 11
With embodiment 7, at H
2/ C
2H
2Investigate the acetylene hydrogenation activity=4 times, reaction result is listed in table 1.
Embodiment 12
With embodiment 1, with mesopore SiO
2For carrier, make that molybdenum phosphorus mol ratio is 1, MoP mass loading amount is that 15% support type phosphatization molybdenum is a catalyst, at 220 ℃ of reaction temperatures, H
2/ C
2H
2=6, following investigation acetylene hydrogenation activity, reaction result is listed in table 1.
Embodiment 13
With embodiment 12, investigate MoP mass loading amount and be the acetylene hydrogenation activity of 20% MoP catalyst, reaction result is listed in table 1.
Embodiment 14
With embodiment 12, investigate MoP mass loading amount and be the acetylene hydrogenation activity of 25% MoP catalyst, reaction result is listed in table 1.
Embodiment 15
With embodiment 12, investigate MoP mass loading amount and be the acetylene hydrogenation activity of 30% MoP catalyst, reaction result is listed in table 1.
Embodiment 16
With embodiment 12, investigate MoP mass loading amount and be the acetylene hydrogenation activity of 35% MoP catalyst, reaction result is listed in table 1.
Embodiment 17
With embodiment 14, investigate the acetylene hydrogenation activity down for 200 ℃ in reaction temperature, reaction result is listed in table 1.
Embodiment 18
With embodiment 14, reaction result is listed in table 1.
Embodiment 19
With embodiment 14, investigate the acetylene hydrogenation activity down for 240 ℃ in reaction temperature, reaction result is listed in table 1.
Embodiment 20
With embodiment 14, at H
2/ C
2H
2Investigate the acetylene hydrogenation activity=8 times, reaction result is listed in table 1.
Embodiment 21
With embodiment 14, reaction result is listed in table 1.
Embodiment 22
With embodiment 14, at H
2/ C
2H
2Investigate the acetylene hydrogenation activity=4 times, reaction result is listed in table 1.
Table 1
As can be seen from Table 1, pure phase MoP catalyst high reaction velocity (33,000~38,000h
-1), in the wide range of reaction temperature (200-240 ℃) have high acetylene catalytic hydrogenation activity and selectivity, reach at 99.5% o'clock at conversion of alkyne and still can keep surpassing 76% hydrogenation selectivity.Support type MoP/SiO
2Catalyst can keep high acetylene catalytic hydrogenation activity and selectivity equally in high reaction velocity and wide range of reaction temperature; Simultaneously, have higher low temperature acetylene hydrogenation activity and selectivity, at low H
2/ C
2H
2Have higher acetylene catalytic hydrogenation conversion ratio and selectivity during mol ratio.