CN1189395A - Compounded active carbon fibre solid catalyst - Google Patents

Abstract

A solid catalyst compounded with active carbon fibre is prepared from zeolite or oxide and active carbon fibre through mechanical mixing, and features the obviously increased reaction activity, improved heat conduction (so no local over-heat), and high antiwear nature.

Description

The composite active carbon fibre solid catalyst

The invention belongs to the catalyst of composite active carbon fibre solid catalyst, particularly zeolite or oxide and the compound composition of activated carbon fiber and the preparation method of this composite catalyst thereof.

Carbon fiber (CF) is used widely at aspects such as Aeronautics and Astronautics, automobile, building materials, boats and ships, light industry, chemical industry, machinery, weaving and senior sports goods.But the CF surface area is little, and active surface area is littler, thereby, be difficult in the catalytic field and use.

The seventies later stage, developed activated carbon fiber (ACF), it be under specific condition, make have the high surface area and a fibrous carbon of active function groups.Because it has the advantage of CF simultaneously, thereby is widely used in aspects such as gas purification, solvent recovery, wastewater treatment, simultaneously, has also possessed the good condition that is applied to catalytic field.

Last some functional group of ACF makes it have the acidity and the basic sites of a certain amount of and certain intensity, and it is direct some chemical reaction of catalysis not only, and can bring into play other catalytic action with some metal function.In conjunction with the distinctive pore structure of ACF, it might be played a significant role in catalytic reaction.At present, many bibliographical informations the effect of independent use ACF as catalyst.But, be the problem that there are two aspects in catalyst with ACF separately.First ACF is the light fibre shape, has the problem of how moulding when directly using as catalyst; Next is how to install when using in industrial production to have an engineering problem in reactor.These two problems have limited the application of ACF in catalytic reaction to a great extent.Up to now, using ACF only to see some article reports (H.Jin, Carbon, 1996 (34), 3,429) separately in catalytic reaction does not see in industry as yet and uses.

Objects of the present invention provide a kind of composite active carbon fibre solid catalyst, the present invention utilizes the original performance of some solid catalyst and combines with the characteristic of ACF, enable to promote catalytic reaction, it be by an amount of activated carbon fiber and solid catalyst mechanically mix, moulding, this composite catalyst is fit to industrial application, can improve the heat transfer and the mass transfer conditions of the reaction system of former solid catalyst institute catalysis, improve reactivity and improve the stability of catalyst.

Olefin hydration is a typical acid catalyzed reaction, and this reaction heat effect is big, needs to carry out under high pressure, low temperature.For fixed bed reactors, the temperature runaway phenomenon that reaction heat caused is the problem that generally runs into.For propylene hydration reaction, temperature runaway easily causes propylene that oligomerisation reaction takes place on solid acid catalyst, and a large amount of heat bodied oils of generation are with the activated centre of covering catalyst and cause catalysqt deactivation.Exothermic effect on the solid acid catalyst and stability thereof become the key issue of olefin hydration reaction.We find that by the contrast test to several unlike materials the introducing of carbon fiber can address this problem well.Because carbon fiber has good thermal conductivity, remedied the bad shortcoming of solid catalyst heat conduction, make the temperature field homogenising of catalytic reaction, avoided because temperature runaway and the catalyst hot-spot phenomenon that exothermic heat of reaction causes, thereby prolonged life of catalyst.In addition, solid acid catalyst is very big to the influence of propylene hydration reactivity to the absorption property of reactant molecule, and how its adsorption capacity of modulation is to improve an active key issue.Because all there are good adsorption effect in the high surface of ACF, special pore size distribution and distinctive functional group to propylene and water, have played macropore effect, more favourable diffusion between its tow in fact again.Experiment shows that solid acid catalyst such as β zeolite are introduced an amount of ACF and be used for the reaction of propylene hydration preparing isopropanol, have not only eliminated the temperature runaway phenomenon of reaction, and reactivity is improved.Because ACF has above-mentioned characteristic, and it is combined with multiple solid catalyst, might facilitation be arranged to a lot of reactions.For example, ACF is joined with TiO ₂In the Hydrobon catalyst for carrier reactivity is increased.In addition, should be noted that the effect of solid catalyst scuff resistance is strengthened in the adding of an amount of ACF in addition.

The present invention is evenly mixed in the mode of mechanical mixture with activated carbon fiber and is made catalyst by carrier molecule sieve or oxide powder.The addition of activated carbon fiber accounts for 5～15% of catalyst gross weight, and the base material kind of activated carbon fiber can be a viscose rayon, also can be polyacrylonitrile fibre.In the described catalyst, molecular sieve is the β type; Oxide is the anatase-type titanium oxide powder.

The present invention significantly improves the activity of such catalysts that adds ACF because the introducing of activated carbon fiber has significantly improved reactivity.Moreover, it has improved the heat-transfer effect of catalyst very significantly, has prevented reaction hot-spot phenomenon effectively, and temperature runaway is controlled, and the isopropyl alcohol selectivity is improved.It is compared with active carbon, and activity exceeds nearly 4 percentage points.The ACF-H beta catalyst has higher mechanical strength, and the catalyst of forming than aluminium glue or silica gel and H β has better stability, has wide industrial and uses.

Embodiment 1

The H type β zeolite of metering is evenly mixed with mechanical system with ACF (length is less than 1mm), and wherein ACF accounts for 15% of gross weight.With mixed sample compressing tablet, moulding, fragmentation, sieving for standby.With the same manner the silica gel of H type β zeolite and same weight and aluminium glue and active carbon are mixed, and pack in the continuous flow reactor of fixed bed with identical order number.With propylene and water is raw material, is 180 ℃ in reaction temperature, and reaction pressure is 3.0MPa, and the propylene volume space velocity is 1200h ^-1Condition under react.It the results are shown in Table 1, and wherein (1) ACF matrix is viscose rayon, and (2) ACF matrix is Dralon, and table 1 is that H β adds the influence of unlike material to the propylene hydration reaction.

Embodiment 2

Get 4 gram Detitanium-ore-type TiO ₂Powder adds thin water aluminium of 0.4 gram plan and 0.4 gram ACF, evenly mixes, and this mixture is used the 16 milliliters of (TiO of solution that contain cobalt nitrate and ammonium molybdate ₂: CoO: MoO ₃=10: 0.2: 1.0 (weight ratio)), dipping is 24 hours under room temperature, electromagnetic agitation, dries 4 hours down at 120 ℃, again 450 ℃ of following roastings 6 hours.The contrast sample is not except that adding the ACF, and all the other are all with last same.

With pulse-little anti--hydrodesulfurization activity of chromatogram arrangement evaluate catalysts, promptly microreactor and chromatograph joint used adopts the method for thiophene pulse sample introduction to measure the thiophene conversion ratio.Catalyst usefulness temperature programmed reduction method is 8 hours times spent from 200 ℃ to 350 ℃, and hydrogen flowing quantity is 50ml/min, fully gives sulfuration with CS2 under 350 ℃, and reaction temperature is 250 ℃-350 ℃, and table 2 is relations of thiophene conversion ratio and temperature.Table 1:

Catalyst	Aluminium glue-H β	Silica gel-H β	Active carbon-H β	ACF-Hβ ????(1)	?ACF-Hβ ????(2)
						The isopropyl alcohol yield	??9.60％	??9.80％	??6.34％	??10.79％	10.28％

Table 2:

Reaction temperature	????250℃	????270℃	????300℃	????350℃
					The present invention	????42％	????64％	????87％	????100％
Comparative Examples	????39％	????53％	????72％	????96％

Claims (5)

1. a composite active carbon fibre solid catalyst is characterized in that it is to include activated carbon fiber and molecular sieve or oxide, evenly is mixed and made in the mode of mechanical mixture.

2. according to the described composite active carbon fibre solid catalyst of claim 1, it is characterized in that the addition of described activated carbon fiber accounts for 5～15% of solid catalyst gross weight.

3. according to the described composite active carbon fibre solid catalyst of claim 1, the base material that it is characterized in that described activated carbon fiber can be viscose rayon or polyacrylonitrile fibre.

4. according to the described composite active carbon fibre solid catalyst of claim 1, it is characterized in that described molecular sieve is a H β type; Oxide is the anatase-type titanium oxide powder.

5. the described composite active carbon fibre solid catalyst of claim 1 is characterized in that packing it into fixed bed applications in the Industrial Catalysis course of reaction.