CN1119194C - Sulfur recovering catalyst carrying nm TiO2 particles and its preparing process - Google Patents

Abstract

The present invention relates to a load type catalyst for sulfur recovery and a preparation method. The carrier used by the catalyst is Al2O3; active aluminum oxide is preferably used as the carrier; materials loaded on the carrier are nanometer TiO2 particles which are mainly distributed between 20 and 100 nm; the specific surface of the catalyst is controlled between 100 and 500m<2>/g and is preferably controlled between 200 and 400m<2>/g; the amount of the nanometer TiO2 particles is 0.1 to 5 wt% of the total amount of the catalyst and is preferably controlled to be 0.5 to 3.0 wt% of the total amount of the catalyst. The preparation method of the catalyst mainly comprises four steps: evaporation, passivation, loading and calcination, and the Claus activity and the CS2 hydrolysis activity of the obtained catalyst are totally superior to that of the conventional catalyst.

Description

Catalyst for recovering sulfur of a kind of carrying nm TiO 2 particles and preparation method thereof

The present invention relates to a kind of catalyst for recovering sulfur, specifically, the present invention relates to a kind of at Al ₂O ₃Last load has nano-TiO ₂The catalyst for recovering sulfur of particle.

In PETROLEUM PROCESSING and gas chemical industry's process, produce a large amount of H that contains ₂The sour gas of S, industrial general employing claus process Recovered sulphur is also eliminated environmental pollution:

(1)

(2)

China's sulfur recovery technical development is very fast, up to now, has built up the sulfur recovery unit of cover more than 60, and the sulphur yield is all about 94% usually.Because the existence of hydro carbons and CO has generated portion C S in the sour gas in combustion furnace ₂And COS:

(3)

(4) on commercial plant, generally remove CS by following catalytic hydrolysis reaction ₂And COS:

(5)

(6)

In the Cross unit that does not have the vent gas treatment measure, the CS that combustion furnace generates ₂Usually will account for more than 20% of tail gas desulphurization amount with COS, if set up the low-temperature Claus tail-gas treating apparatus, organic sulfur compound more will account for more than 50% of tail gas total sulfur loss.Therefore, the quality of claus catalyst tempreture organic sulphur hydrolysis activity has become the key of further raising Cross unit total sulfur recovery.

Because it is the main cause that causes catalyst activity to reduce that sulfation is poisoned, for improving the organic sulfur hydrolysis rate of catalyst for recovering sulfur, recent two decades comes, and people are devoted to develop new auxiliary agent type catalyst for recovering sulfur to improve H ₂S conversion ratio and COS/CS ₂Percent hydrolysis also prolongs life of catalyst, wherein mainly contains TiO ₂-Al ₂O ₃, NaO-Al ₂O ₃, CaO-Al ₂O ₃Catalyst etc. are wherein especially with TiO ₂-Al ₂O ₃The catalytic effect of catalyst is best.

U.S.P.4141962 has introduced a kind of TiO ₂-Al ₂O ₃The preparation method of auxiliary agent type catalyst for recovering sulfur, this catalyst is to be 300m with the specific area ²/ g, external diameter are the Al of φ 2-4mm ₂O ₃Ball spraying TiCl ₄Back drying is handled, and carries out 500 ℃ * 4h roasting and form.With active A l ₂O ₃Compare this TiO ₂-Al ₂O ₃Catalyst has stronger anti-sulfation poisoning capability, higher tempreture organic sulphur hydrolysis ability and longer life-span.Pollute but exist than overall situation in this catalyst preparation process, realize difficulty of industrialization.

Nano material crystal grain tiny (1-100nm), atomicity on its crystal boundary is more than crystals, thereby make nano material that many performances that are different from general coarse grain material be arranged, and size is little, specific area is big, surface key attitude is different with inside with electronic state, the not congruent increase that causes the surface-active position of surface atom coordination, and this just makes it possess condition as efficient catalyst.

Purpose of the present invention just provides a kind of at Al ₂O ₃Load has nano-TiO on the body ₂Catalyst for recovering sulfur of particle and preparation method thereof.

In catalyst for recovering sulfur of the present invention, selected carrier is Al ₂O ₃Carrier, the material of institute's load is a nano-TiO ₂Particle, and the specific surface of catalyst is controlled at 100～500m ²Between/the g, preferably the specific surface with catalyst is controlled at 200～400m ²Between/the g.Measure the method for specific surface and can use ethanol adsorption dehumifier method.

Al ₂O ₃Carrier is preferably selected active A l for use ₂O ₃, also promptly preferably select the Al of various middle transition attitudes for use ₂O ₃, comprise γ type, ρ type, χ type etc., because such Al ₂O ₃Have than higher specific surface, be easy to carry out the load of nanometer particle material, the nano particle in the load is difficult drop-off also.

The nano-TiO of institute's load on the catalyst ₂The size of particle mainly is distributed between 20～100nm.Particle size is controlled in such scope, can give full play to the superiority of nanometer particle material on the one hand, and preparation is simultaneously got up and realized than being easier to.Measure nano-TiO ₂The method of particle can adopt transmission electron microscope method (TEM).

In the present invention, nano-TiO ₂The crystal structure of particle is mainly rutile-type.Measure nano-TiO ₂The crystal structure of particle can adopt χ optical diffraction method.

Nano-TiO ₂Particle shared content in catalyst generally is controlled between 0.1～5wt%.Nano-TiO ₂The content of particle is too low, as is lower than 0.1wt%, just can not fully demonstrate the advantage of nano material; Nano-TiO ₂The content of particle is too high, as is higher than 5wt%, and it is oversize then to carry out the shared time of load, and is easy to generate the accumulation of nano particle, and not only cost increases, and is unfavorable for bringing into play the advantage of nano material.

In the present invention preferably with nano-TiO ₂The content of particle is controlled between 0.5～3.0wt%.

When preparing catalyst of the present invention, mainly may further comprise the steps: (a) make the Titanium evaporation, obtain the nano metal titanium particle; (b) the above-mentioned nano metal titanium particle that obtains is extracted in the sample storage chamber, carries out Passivation Treatment; (c) above-mentioned nano metal titanium particle through Passivation Treatment is loaded into Al ₂O ₃On the carrier; (d) then with the above-mentioned Al that loads the nano metal titanium particle ₂O ₃Carrier can obtain at Al at 300～700 ℃ roasting temperature ₂O ₃Load has nano-TiO on the carrier ₂The catalyst for recovering sulfur of particle.

In step (a), used Titanium can be bigger reguline metal titanium, used method of evaporating can be selected laser method, radio frequency plasma method or arc plasma process for use, and these methods can make dystectic titanium evaporation, makes it to condense on the cold-trap to obtain the nano metal titanium particle.

In step (b), can use the air-flow round-robin method that the nano metal titanium particle that makes in the step (a) is extracted in the sample storage chamber, pass to air then titanium particle is carried out oxidation and makes it passivation.

In step (c), can adopt powerful alluvium logos that the passivation nanometer titanium particle that makes in the step (b) is loaded into Al ₂O ₃On the carrier.Al ₂O ₃Carrier should have bigger specific surface, so that the loading of nanometer titanium particle, generally its specific surface is at 100～500m ²In the scope of/g, be preferably in 200～400m ²In the scope of/g.Al ₂O ₃Preferably select active A l ₂O ₃, also promptly preferably select the Al of various transition states for use ₂O ₃, comprise γ type, ρ type, χ type etc., because active A l ₂O ₃Has higher specific surface.

In step (d), the temperature of roasting should not be too high, otherwise carrier structure is had greatly changed, and causes the loss of specific surface, also makes the coalescent change of nanometer titanium particle big easily simultaneously; Sintering temperature is too low, and the nanometer titanium particle is firm inadequately with combining of carrier, and in the use of catalyst, nano particle comes off easily later on.So better sintering temperature scope is 400～600 ℃ in the step (d).The time of roasting generally was controlled between 2～10 hours.In addition, after step (d), the nano metal titanium particle is converted into nano-TiO ₂Particle.

Because the present invention adopts the method for physics to prepare the nano metal titanium particle, obtain nano-TiO through roasting again ₂Catalyst, thus method of the present invention be a kind ofly do not pollute, environment amenable method for preparing catalyst, and catalyst of the present invention is because load has nano-TiO ₂Particle, its Crouse's activity and CS ₂Hydrolysing activity all is better than the industrial Al that generally uses ₂O ₃Catalyst is a kind of TiO efficiently ₂-Al ₂O ₃Catalyst for recovering sulfur.

Below in conjunction with embodiment to nano-TiO of the present invention ₂-Al ₂O ₃Catalyst for recovering sulfur and preparation method thereof further describes, but scope of the present invention is not limited only to following embodiment.

Embodiment 1

Use the bulk metal titanium as raw material, as thermal source, make high-melting-point titanium fusing evaporation, and make it to condense to and obtain the nano metal titanium particle on the cold-trap with the arc-plasma of high-power high-energy; Use the air-flow round-robin method that it is retracted in the sample storage chamber then.Utilize transmission electron microscope (TEM) to observe the morphosis of the Titanium particle that makes, find that the particle diameter distribution of nano metal titanium is more even, spherical in shape or polygon mainly is distributed between 20～50nm.

With the above-mentioned nanometer Ti particle that makes in Ti: Al=2: 1000 ratio, use powerful alluvium logos to be loaded into the Al that external diameter is 0.1～0.15mm ₂O ₃On the particle, 550 ℃ of roastings 3 hours, make loaded nano TiO then ₂/ Al ₂O ₃Catalyst A.

The catalyst A surface layer peeling is got off to make sample, observe by low power transmission electron microscope (TEM), find to have the particle of two kinds of contrasts to exist, the amorphous substance of loose grey is Al ₂O ₃, the spherical material of black class is TiO ₂, granularity mainly is distributed between 20～60 nanometers.

Then, catalyst A is carried out χ optical diffraction mensuration, finds nano-TiO ₂Particle is mainly the rutile phase.Among the present invention, the nano metal titanium becomes TiO, TiO through high-temperature oxydation ₂, variation of valence has taken place in metallic, and titanium is mainly with the TiO of rutile-type ₂Form exist, the content of TiO is lower.TiO before and after loading ₂The XRD characterization result show, utilize the nanometer Ti of method such as hydrogen arc plasma process preparation, handle through rear oxidation, the primary product of generation is a rutile titanium dioxide.

The specific surface that records catalyst A with ethanol adsorption dehumifier method is 310m ²/ g.

Embodiment 2

Prepare loaded nano TiO by embodiment 1 same method ₂/ Al ₂O ₃The ratio of catalyst B, but Ti: Al is 4: 1000, and sintering temperature is 580 ℃.Measure by embodiment 1 same method, record TiO in the catalyst B ₂Particle diameter mainly is distributed between 20～70nm, and the specific surface of catalyst B is 300m ²/ g.Embodiment 3

Prepare loaded nano TiO by embodiment 1 same method ₂/ Al ₂O ₃The ratio of catalyst C, but Ti: Al is 8: 1000, and sintering temperature is 500 ℃.Measure by embodiment 1 same method, record TiO among the catalyst C ₂Particle diameter mainly is distributed between 20～70nm, and the specific surface of catalyst C is 326m ²/ g.

Embodiment 4

Prepare loaded nano TiO by embodiment 1 same method ₂/ Al ₂O ₃The ratio of catalyst D, but Ti: Al is 10: 1000, and sintering temperature is 400 ℃.Measure by embodiment 1 same method, record TiO among the catalyst D ₂Particle diameter mainly is distributed between 20～75nm, and the specific surface of catalyst D is 357m ²/ g.

Embodiment 5

Prepare loaded nano TiO by embodiment 1 same method ₂/ Al ₂O ₃The ratio of catalyst E, but Ti: Al is 20: 1000, and sintering temperature is 380 ℃.Measure by embodiment 1 same method, record TiO among the catalyst E ₂Particle diameter mainly is distributed between 20～80nm, and the specific surface of catalyst E is 328m ²/ g.

Embodiment 6

Prepare loaded nano TiO by embodiment 1 same method ₂/ Al ₂O ₃The ratio of catalyst F, but Ti: Al is 30: 1000, and sintering temperature is 600 ℃.Measure by embodiment 1 same method, record TiO among the catalyst F ₂Particle diameter mainly is distributed between 20～80nm, and the specific surface of catalyst F is 290m ²/ g.Embodiment 7

Prepare loaded nano TiO by embodiment 1 same method ₂/ Al ₂O ₃The ratio of catalyst G, but Ti: Al is 50: 1000, and sintering temperature is 620 ℃.Measure by embodiment 1 same method, record TiO among the catalyst G ₂Particle diameter mainly is distributed between 20～85nm, and the specific surface of catalyst G is 283m ²/ g.

Embodiment 8

The internal diameter of respectively the catalyst 5ml of the foregoing description 1～7 preparation being packed into is in the stainless steel reactor of 10mm, and reacting furnace adopts Electric heating.The quartz sand mixing preheating of catalyst top filling same particle sizes.Adopt H in day island proper Tianjin GC-14B gas chromatograph on-line analysis reactor inlet and the exit gas ₂S, SO ₂, COS, CS ₂Content, adopt the GDX-301 carrier to analyze sulfide, adopt the 5A molecular sieve to analyze O ₂Content, 120 ℃ of column temperatures adopt thermal conductivity detector (TCD), and 150 ℃ of detector temperatures are done carrier gas with hydrogen, flow velocity 28ml/min behind the post.

With For the index reaction, investigate nano-TiO ₂/ Al ₂O ₃The tempreture organic sulphur hydrolysis activity of catalyst for recovering sulfur, inlet gas is formed: CS ₂1% (v/v), SO ₂1% (v/v), O ₂1500ppm, H ₂O30% (v/v), all the other are N ₂, the gas volume air speed is 12500h ^-1, reaction temperature is 370 ℃.Calculate the CS of catalyst according to following formula ₂Percent hydrolysis: ${\mathrm{\&eta;}}_{\mathrm{CS}2}=\frac{C_0-C_1}{C_0}\&times;100\%$ C wherein ₀, C ₁Be respectively inlet and outlet CS ₂Volumetric concentration.The CS of catalyst sample A～F ₂Percent hydrolysis is listed in table 1.As can be seen from Table 1, with nano-TiO ₂The increase of content, the CS of catalyst ₂Percent hydrolysis obviously increases, but works as nano-TiO ₂Content is increased at 2% o'clock, the CS of catalyst ₂Percent hydrolysis reaches balance substantially.

The CS of table 1, different catalysts sample ₂Percent hydrolysis

Catalyst sample	A	B	C	D	E	F	G
								η CS2	48	57	67	73	77	78	78

Embodiment 9

According to embodiment 8, with For the index reaction, investigate nano-TiO ₂/ Al ₂O ₃Crouse's activity of catalyst for recovering sulfur, reacting gas is formed: H ₂S2% (v/v), SO ₂1% (v/v), O ₂1500ppm, H ₂O30% (v/v), all the other are N ₂, the gas volume air speed is 12500h ^-1, reaction temperature is 300 ℃. and calculate Crouse's conversion ratio of catalyst according to following formula: ${\mathrm{\&eta;}}_{H2S+\mathrm{SO}2}=\frac{M_0-M_1}{M_0}\&times;100\%$ M wherein ₀, M ₁Then representative enters the mouth and exit H respectively ₂S and SO ₂Volumetric concentration and.Crouse's conversion ratio of different catalysts is listed in table 2.As can be seen from Table 2, Crouse's conversion ratio of different catalysts sample is with nano-TiO ₂The increase of content has increase slightly, but changes little.

Crouse's conversion ratio of table 2, different catalysts sample

Catalyst sample	A	B	C	D	E	F	F
								η H2S+SO2	65	66	67	67	67	67	67

Embodiment 10

According to embodiment 8, keeping gas space velocity is 5000h ^-1, all the other conditions are constant, investigate SO ₂/ CS ₂Variation to nano-TiO ₂/ Al ₂O ₃The influence of catalyst sample E hydrolysing activity the results are shown in table 3.As can be seen from Table 3, with SO ₂/ CS ₂The increase of ratio, the percent hydrolysis of catalyst descends, but nano-TiO ₂/ Al ₂O ₃The catalyst decline scope is starkly lower than common Al ₂O ₃, nano-TiO is described ₂/ Al ₂O ₃Anti-sulfation poisoning capability be better than common Al ₂O ₃Catalyst.

Table 3, SO ₂/ CS ₂Variation to nano-TiO ₂/ Al ₂O ₃The influence of catalyst sample E hydrolysing activity

SO 2/CS 2	0.5	1.0	2.0
				Catalyst sample E	99	94	83
Common Al 2O 3	98	85	76

Embodiment 11

According to embodiment 8, keeping gas space velocity is 5000h ^-1, all the other conditions are constant, investigate temperature to nano-TiO ₂/ Al ₂O ₃The influence of catalyst sample E hydrolysing activity the results are shown in table 4.As can be seen from Table 4, with the rising of temperature, CS ₂Percent hydrolysis obviously raise but nano-TiO ₂/ Al ₂O ₃Low temperature active obviously be better than common Al ₂O ₃Catalyst, when temperature reached 370 ℃, the percent hydrolysis of the two reached unanimity substantially.Table 4, temperature are to nano-TiO ₂/ Al ₂O ₃The influence of catalyst sample E hydrolysing activity

Temperature, ℃	280	320	340	370
					Catalyst sample E	70	90	97	99
Common Al 2O 3	43	78	94	99

Embodiment 12

According to embodiment 8, all the other conditions are constant, investigate air speed to nano-TiO ₂/ Al ₂O ₃The influence of catalyst sample E hydrolysing activity the results are shown in table 5.As can be seen from Table 5, with the increase of gas volume air speed, CS ₂Percent hydrolysis obviously reduces, but nano-TiO ₂/ Al ₂O ₃The more common Al of amplitude that reduces ₂O ₃Much smaller, nano-TiO is described ₂/ Al ₂O ₃Active high, can under big air speed, use.Table 5, air speed are to nano-TiO ₂/ Al ₂O ₃The influence of catalyst sample E hydrolysing activity

Air speed, h -1	2500	5000	12500
				Catalyst sample E	99	95	78
Common Al 2O 3	98	90	44

Claims (9)

1, a kind of catalyst for recovering sulfur of support type, the used carrier of catalyst is Al ₂O ₃, the material that it is characterized in that institute's load on the catalyst carrier is a nano-TiO ₂Particle, particle size distribution are between 20～100nm, and the specific area of catalyst is controlled at 100～500m ²Between/the g.

2, the described catalyst of claim 1 is characterized in that the specific area of catalyst is controlled at 200～400m ²Between/the g.

3, the described catalyst of claim 1 is characterized in that the used carrier of catalyst is an activated alumina.

4, the described catalyst of claim 1 is characterized in that the nano-TiO of institute's load on the catalyst ₂Particle is mainly rutile-type.

5, claim 1 or 4 described catalyst is characterized in that the nano-TiO of institute's load on the catalyst ₂The amount of particle accounts for 0.1～5wt% of catalyst total amount.

6, the described catalyst of claim 5 is characterized in that the nano-TiO of institute's load on the catalyst ₂The amount of particle accounts for 0.5～3.0wt% of catalyst total amount.

7, a kind of method for preparing above-mentioned support type catalyst for recovering sulfur comprises the following steps: that (a) makes the Titanium evaporation, obtains the nano metal titanium particle, and particle size distribution is between 20～50nm; (b) the above-mentioned nano metal titanium particle that obtains is extracted in the sample storage chamber, carries out oxidation, make it passivation; (c) above-mentioned nano metal titanium particle through Passivation Treatment is loaded into Al ₂O ₃On the carrier; (d) then with the above-mentioned Al that loads the nano metal titanium particle ₂O ₃Carrier can obtain at Al at 300～700 ℃ roasting temperature ₂O ₃Load has nano-TiO on the carrier ₂The catalyst for recovering sulfur of particle, nano-TiO ₂Particle size distribution is between 20～100nm.

8, the described preparation method of claim 7 is characterized in that the method that makes Titanium become the nano metal titanium particle in the step (a) adopts laser method, radio frequency plasma method or arc plasma process.

9, the described preparation method of claim 7 is characterized in that sintering temperature in the step (d) is controlled in 400～600 ℃ the scope.