JPS5817835A - Catalyst for selective hydrogenation - Google Patents

Abstract

PURPOSE:To obtain a catalyst for selective hydrogenation of acetylene having high activity and high selectivity by depositing palladium on a carrier which consists essentially of alumina and has pore distributed in both micro and mesomacro sizes. CONSTITUTION:Pd is deposited on a carrier of 55-120m<2>/g specific surface area consisting essentially of alumina of which at least part is theta type crystals whereby a catalyst for hydrogenation is obtained. This catalyst has 0.4-1.0cc/g total capacity of pores of 37.5-75,000Angstrom radii of which the capacity of pores of 37.5-150Angstrom radii and the capacity of pores of 150-3,000Angstrom radii is at least 0.1cc/g. The content of said Pd is in a 0.02-0.4wt% range based on the weight of the carrier. Said carrier has the pore distributions that possesses each one distinct peak at 40-150Angstrom and 150-3,000Angstrom radii respectively. The above-mentioned carrier is obtained by kneading alumina raw material and carbon black and molding the mixture then calcining the molding in an oxidiative atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a catalyst for selective hydrogenation of acetylene compounds.

In the petrochemical industry, large amounts of ethylene or propylene are produced by thermal decomposition of naphtha, natural gas, etc., but each olefin fraction obtained contains small amounts of acetylene compounds such as acetylene, methylacetylene, etc. has been done. In chemical reactions using these olefins as raw materials, the contamination of acetylene compounds is often avoided; therefore, acetylene compounds are usually selectively hydrogenated using a catalyst containing palladium supported on a refractory support such as alumina. Refined.

However, in such olefin O refining, since the reaction is carried out in the presence of an equivalent amount or more of hydrogen to the acetylene compound in the olefin atmosphere, the excess hydrogen is added to the olefin and low-value paraffins are produced. Undesirable side reactions are induced. Although it is necessary to make the supply ratio of paraffin by-products as close to equimolar as possible, the removal rate of acetylene compounds decreases as the amount of excess hydrogen decreases.

In order to solve this dilemma, there is a long-awaited development of highly active and highly selective catalysts that can selectively remove acetylene compounds while reducing the amount of excess hydrogen. Several proposals have been made.

FlJ, tif, catalysts in which a co-component such as chromium is added to palladium, and palladium catalysts in which the pore diameter is controlled within a predetermined range and 9-alumina is used as a carrier have been cited as having the effect of improving smoothness.

As a result of various studies aimed at improving the activity and selectivity of a round palladium catalyst that selectively hydrogenates and removes acetylene compounds in olefins, the present inventors found that at least a portion of them are C-type crystals. A catalyst in which palladium is supported on a support mainly composed of alumina and having a specific surface area of j3~l/l, and the total volume of the pores with a radius of JtsX to zooooX is a~A Oee/f. , and radius J
Both the pore volume of tsX to 1soL and the pore volume of radius iso to 5ooo@ are at least Q/ec
The present invention was achieved based on the discovery that a catalyst characterized by:

The present invention will be explained in detail below.

θ The catalyst according to the present invention has a specific surface @SS ~ 120w1/l in which at least part of it is mainly composed of monocrystalline alumina.
, preferably a catalyst in which palladium is supported on a carrier having a radius J of 3X to 5oooX, in which the total volume of the pores is a~tocc/f, and the radius is Both the pore volume of 72 s K to 1 so
A catalyst characterized by (:e / ),
Normally, the pore distribution exhibits a distinct peak from 4IoX to tsoX and from radius 1soX to 5oooX.

The carrier preferably has an alumina component of 60 or more, and of course an alumina ioo'lk carrier can also be used. Components other than aluminium and mina that can constitute the carrier include refractory oxides of silica, titania, zirconia, and magnesia fat. .

The catalyst according to the present invention (hereinafter referred to as the present catalyst) has an intermediate surface area of 1/Owl/F as described above and a large number of flK pores on both micro and meso sides. There is something about it.

In general, when hydrogenating and removing acetylene compounds in olefins, what is the specific surface area of the carrier? A large catalyst tends to have high activity but poor selectivity, and a catalyst with a small carrier specific surface area tends to have high selectivity but low activity.

However, the catalyst carriers used in practical use are those that also contain α-alumina and have a small specific surface area of 3~J Ovrl/fl, or are made of r-alumina/10~5
It is limited to those with a large specific surface area of oOvrl/l, and either activity or selectivity is often sacrificed. This is because it is difficult to produce an alumina support with an intermediate specific surface area. At the same time, this is due to the fact that the performance of catalysts obtained from such supports is not necessarily satisfactory per se.

On the other hand, the carrier used for this catalyst is SS~/JO
It has an intermediate specific surface area of gl/f, holds a considerably larger pore volume than alumina-based carriers that normally have a specific surface area of this level, and has a relatively medium pore volume of 5 tzX to tsoX in radius. Pores are distributed in both pores and meso-macro pores from /30 μm to 5oooL.

Surprisingly, a catalyst in which palladium is supported on such a carrier achieves extremely high activity and high selectivity at the same time.

The reason for this is not entirely clear, but the relatively high specific surface area imparts activity by appropriately dispersing radium, and at the same time, the special pore structure improves selectivity. It is said to be great.

To produce an alumina support with spinning properties used as a support for this catalyst, carbon black is mixed with activated alumina such as %r-alumina or η-alumina, or alumina raw material such as alumina, and water and optionally It can be manufactured by adding a molding aid, kneading and molding, and then firing in an oxygen-containing air stream to remove carbon black by firing.

As carbon black mixed with alumina raw material, i
Particle sizes in the range of so to 5oooX units are used. The position and width of the pore distribution of the resulting aluminum carrier will depend on the particle size of the carbon black and the size of the stractures. greatly affected.

The size of the stractures is determined by the oil absorption amount of carbon black (for example, DIP absorption amount; carbon black 10
0ftIC capacity of diptylphthalate absorbed, expressed in units -/10at). And with normal carbon black, its DIIP absorption amount is about 60~JO
Od//00 f, JOOd/ノ00 for special ones
There are also more than f.

There are no particular restrictions on the type of carbon black that can be used, but commercially available carbon blacks such as channel blacks such as Mitsubishi Carbon Black 4#100 and f1400 (manufactured by Mitsubishi Chemical Industries, Ltd.), Diablackkum, Diablack H (Sanbin), etc. Furnace black (manufactured by Kasei Kogyo ■), Asahi Su-Marute (manufactured by Asahi Carbon ■), Denka Acetylene (manufactured by Denki Kagaku Kogyo ■), Ketjen Black 1
ec (manufactured by Akzochemy), etc.

During molding, the alumina raw material and carbon black should be mixed as uniformly as possible in order to obtain better physical properties. The amount of carbon black added to the alumina raw material is S to 120% by weight, preferably 10 to 100% by weight. When using additives that disappear by firing, the amount of additives should be at most the upper limit / D' weight in order to avoid impairing the strength and other physical properties of the resulting molded product. However, in the present invention, when producing an alkaline carrier, the amount of carbon black added is extremely large. Moreover, it is quite surprising that such large additions provide controlled locations and amounts of bores, yet do not impair the required physical properties.

The raw material alumina and carbon black that have been uniformly mixed in this manner are further mixed and mixed with water and other forming aids if necessary, and then formed into a desired shape. Well-known molding methods include tableting,
There are extrusion methods, extrusion-marmo methods, transfer granulation methods, and briquerating methods, among which extrusion molding is an easy and versatile molding method.

The molding method will be explained by taking as an example the case in which a 100% polyester resin is used. For example, Suit martyrdom - 100 copies of Might
Part O of carbon black is added, mixed uniformly with a mixer, and then transferred to a kneader, where water and auxiliary agents are added and mixed. Preferred auxiliaries include inorganic acids, organic acids or ammonia, hydrazine, aliphatic amines, aromatic amines,
Examples include basic nitrogen compounds such as heterocyclic amines, and organic substances such as polyvinyl alcohol. The kneaded product thus obtained is then extruded using an extruder through a die hole of a desired size. If desired, the molded product may be aged in a closed container.The molded product is then dried and treated with phosphorous oxide, and finally has properties as a carrier. However, oxidation firing company,
This must be accomplished very carefully, since carbon black is flammable and there is a high risk of high temperatures. Even if the temperature is below the upper limit temperature, a sudden rise in temperature is not desirable.

The firing temperature necessary to burn and remove the carbon black as described above is at least S.O.C.C., and the final firing temperature for obtaining the desired alumina used in the present invention is #! EB%to
The firing time is not particularly limited, but is usually about 1 hour to 1 day.

Thus, an alumina support is obtained which has good mechanical strength, abrasion resistance and physical properties such as large surface area, large pore volume, and characteristic pore distribution.

There is no particular restriction on the size of the carrier, but since the hydrogenation of acetylene compounds in olefins is usually carried out in a fixed bed, a size of about 100 to 1000 ml is preferable. , spherical, tablet-like, or crushed products thereof.

The amount of palladium supported on the above-mentioned carrier is usually aoi to I weight relative to the carrier, preferably (102 to a
# It is heavy and in many cases is concentrated on the surface of the carrier.

As raw materials for palladium used in K for producing this catalyst, common palladium compounds such as palladium chloride, palladium nitrate, potassium chloropalladate, sodium chloropalladate, palladium oxide, and palladium ammine complex salts are used. Palladium loading is before.

The above palladium compound is dissolved in a solvent such as water.

The palladium compound can be supported by a known supporting method such as a dipping method, a spraying method, or a precipitation method, and then reduced.

Catalyst #i supporting a palladium compound is not used for the reaction after drying, or if harmful substances to the reaction such as chlorine radicals and nitrate radicals remain, heat treatment,
It is used after being subjected to reduction treatment or water washing treatment.

Furthermore, a catalyst with even higher performance can be obtained by the method described below. That is, after the carrier is impregnated with a solution of a palladium compound, it is dried, calcined and reduced as necessary, and further immersed in K (1) an oxygen-containing organic compound or its aqueous solution or a hydrocarbon having j to 30 carbon atoms. Then, under a gas atmosphere containing molecular oxygen, 300 to 400
or (2) reduction at 100-400°C in a methanol-containing gas atmosphere, followed by oxidation at DO~600°C in a molecular oxygen-containing gas atmosphere. What is the amount of carbon monoxide adsorbed at ℃? Adjust to S-73 or higher.

In the above treatment (1), examples of the oxygen-containing organic compound include aliphatic alcohols such as methanol and ethanol, aliphatic carbonaceous compounds such as vinegar beak, propionic acid, and starch. Aliphatic carboxylic acids and starches are usually used as aqueous solutions, but aliphatic alcohol 2 may be used as is or as an aqueous solution. As the hydrocarbon having -J0 carbon atoms, aliphatic hydrocarbons are used, preferably aliphatic unsaturated hydrocarbons, particularly StOα-olefins having 4 to 4 carbon atoms. The immersion temperature is arbitrarily selected within the range of room temperature to about 200°C, and 1
Although the immersion treatment is carried out for an hour to 10 days, a longer immersion treatment under milder conditions provides more favorable results in terms of catalyst life. The immersed catalyst is then calcined at 300 to 400° C. in an atmosphere of molecular oxygen-containing gas to oxidize and remove attached oxygen-containing organic compounds and hydrocarbons. The above process (1) can be repeated two or more times as desired.

In the process (2) above, gaseous methanol which has been methanoled with an inert gas such as nitrogen is used as the methanol-containing gas, and gaseous methanol which has been methanoled with an inert gas such as nitrogen is used as the molecular oxygen-containing gas. Oxygen gas diluted to laO@bone% is used. The processing time for both these reduction and oxidation treatments is not particularly limited, but usually / -7
A treatment time of 0 hours is sufficient. Also, (2) above
This process can be repeated two or more times if desired.

In the present invention, the catalyst prepared by the method explained and explained above is more accurately referred to as a catalyst precursor, and the palladium in the catalyst is not completely in the form of metallic palladium. However, when used as is for the hydrogenation removal of an acetylene compound, it is quickly reduced within the reaction system and exhibits a catalytic action, so it can be used in the reaction without any special reduction treatment.

However, in order to maintain the initial reaction stably,
It is preferable that the above-mentioned catalyst is previously subjected to a reduction treatment before use. Is the reduction sensitive layer under a reducing gas atmosphere, which is supposed to be hydrogen gas?
If! The process is carried out at a temperature of +3°C to JOO°C.

This catalyst is used in the reaction of hydrogenating acetylene compounds to the olefin stage, especially naphtha.

It is effective in the reaction of selectively hydrogenating acetylene compounds in olefins such as ethylene and tetrapyrene obtained by thermal decomposition of hydrocarbons such as natural gas.

When the reaction is carried out by the so-called post-hydrogenation method, the amount of hydrogen gas required for the reaction is /-3 times the mole of the acetylene compound in the raw material gas. Not only does the yield increase, but the heat of reaction is large, making it difficult to control the reaction temperature.

The reaction temperature is variable depending on the desired removal rate of the acetylene compound and the molar ratio of hydrogen gas to the acetylene compound, but it is preferably as low as possible, and is usually selected within the range of room temperature to 200°C. The reaction pressure is selected within the range of Tsuneta to about 30 g AFE.

Since the above reaction has an extremely high reaction rate, it is possible to increase the space velocity. Normally, the gas space velocity is within the range of 100 to 10,000 Hr-'' in terms of standard conditions.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless it deviates from the spirit thereof.

In the following examples, the amount of carbon monocide adsorbed on radium on the carrier was determined by the method described below. Then 1svt
After the /-shaped tube ('), connect the gas flow path to the heat conduction cell of the gas chromatograph in advance so that it can be recorded. Next, inject 3θ μt of CO gas with a microsyringe in the H gas flow. From the entrance.

Pulse injection-Jru. The peaks of III adsorbed on the catalyst and the adsorption layer are recorded, and the difference is taken as the amount of CO adsorbed on the catalyst. Repeat the CO pulse KJ, J times and confirm that no CO is adsorbed after the a time. Finally, accurately weigh the amount of catalyst and calculate the amount of CO adsorption per catalyst.

In addition, a reaction test using the prepared catalyst was conducted in the following manner.

The prepared catalyst/j- was packed into an 808J/4 reactor with an inner diameter of 0 mm, heated to 60°C, and hydrogen gas was passed through it for 1 hour to reduce the catalyst.
Nitrogen Itk'ip, Acetylene Q! Unfortunately, hydrogen 10%, -
Gas with the composition of carbon oxide aooi (unit: volume 96) at 60°C, k#/cd a per hour? j NZ
(GH8V kooobr-") to remove acetylene in ethylene by hydrogenation, the 0 reactor volume log gas was analyzed by gas chromatography, and the selectivity was calculated according to the following formula.

Italy, []5. ... Reactor inlet concentration [ ]. 1...
Reactor outlet concentration Δ(Cz”)−[C1”lB, [c, “′].

The pore distribution and amount in the examples were measured using a water@sennin type porosimeter. The machine used is a borosimeter series Koooo made by Carlo Erba, with a maximum pressure of 41/CDL gauge/gauge. Therefore, the measurement range of the pore is from radius 37sX to tsoooK.

The surface area was determined by the BIT method using the Chapter 9 adsorption method. The machine used is Numptomatic 1too manufactured by Carlo Erba.

The wood compressive strength #Fh and the breaking load in the radial direction of the extrusion molded product (47 pieces) were measured using a Kashaya type hardness tester, and the average value of 20 pieces was adopted.

In addition, Table 7 shows the physical property values of carbon black used in the following examples.

Table-I DBP absorption amount: Example 1 of paper measurement using ASTM n Kodalder 79 Boehmite powder Paral BB (A40
．． Containment rate?) Coco? and carbon black Aa
Zj) (30 weight for boehmite: 96) After dry mixing in a lamixer for 60 minutes, this was transferred to a patch kneader (inner capacity: 100 g) to GC, and @3% nitric acid aqueous solution Coco 01 was mixed with approx.
The mixture was added in portions while kneading, and mixing was continued for an additional 23 minutes.

Next, add 1 part of aqueous ammonia/aty to the mixture,
After kneading for 23 minutes, use a complete screw extruder to create a diameter of J! -Extrusion molded. After drying the molded product at l-0°C for 3 hours, the temperature was gradually raised in an electric furnace under drying air flow, and it was fired at 600°C for 3 hours, and then at /100°C for 3 hours to form alumina. A carrier was obtained. The diameter of the extruded product after firing is about 2 cm, and the average wire strength is about 2 cm.
It was ke. Further, the specific surface area was 100 d/fl.

The analysis results of this alumina support by X-ray diffraction were consistent with the data for theta alumina described in the Catalyst Society of Japan's Elemental Catalyst Handbook (Chijin Shokan), pages 17-11.

The pore volume and pore distribution of this alumina support were as follows.

Pore capacity Qdac from radius 3nλ to 1soX
f radius/pore volume Qko from soX to 5oooX
k ce/ f Total pore volume *<32sK~ri5oooλ) OA f Ic
e/f Modest pore radius (radius where distribution shows maximum) qoX and 2
30A The pore distribution curve of this alumina support is shown in FIG.

Next, convert this alumina carrier CO001 into palladium chloride equivalent value? and immersed in an aqueous solution 400ml containing OJml of hydrochloric acid for 1 hour, then drained and dried at 120°C for about 1 hour to support palladium chloride in terms of palladium on QOj heavy aS alumina and prepare a catalyst (catalyst - IO) tl. -I got it. Catalyst〒
10 co@I was 7S/f pd, and the pore distribution curve was almost identical to that of the alumina support.

Catalyst-io was immersed in a mixed α-olefin having carbon atoms of 1 to 11 at f/DO°C for 3 hours, then drained, filled into a glass tube, and heated at KQOO°C for 1 hour under air circulation at 413°C.
It was calcined at 0°C for 3 hours to obtain a catalyst -//. Catalyst-//
The amount of CO adsorbed was dtη/9-PI. When the reaction test was conducted using Catalyst-10 and Catalyst-/L, the results shown in Table 2 were obtained.

Corr-J and 'J were obtained by changing the final firing temperature to 7200°C.

Various physical property values of the obtained alumina carrier were as follows.

Soil shrinkage strength, 3.7 square/ke specific surface area &, 7 tn/P pore volume <3q
, Tono! IOk') 0/40 CC/ 7(/!;
0~30θOA) θ300 1(313~730
00k) QQI,! r #modest pore radius
9.7A and TecoOA are shown in the pore distribution-st-g diagram of this alumina support.

Next, palladium chloride was supported on this alumina carrier in the same manner as in Example 1, and the supporting ratio aOS weight in terms of palladium was adjusted to about $-20. Catalyst - 10 CO absorption amount 8
The pore distribution curve #sFi was almost the same as that of the alumina support.

Further, Catalyst Jo was immersed in α-olefin and calcined in exactly the same manner as in Example 1 to obtain Catalyst Jo.

Catalyst-J/NOC01lil amount 11ittay/y-pa
There was a time. When an oil mud reaction test was conducted using Catalyst-0 and Catalyst-Col, the results shown in Table 2 were obtained.

Comparative Example 1 An alumina carrier was produced in the same manner as in Example 1 except that the final firing temperature #1 was changed to 700Q''C.The physical properties of the obtained carrier were as follows.

Details 9! J [104 勺′ Specific surface area 13j 1 m pore capacity radius (, y 2 to 1 zoX) abitcc 7
y(tsoS-soooX) air#(JtS~4
! 000^)d? ? J# Modest pore radius goX and 100
First, palladium was supported on this carrier in the same manner as in Example I, and the palladium loading rate aOS weight was finally determined. Catalyst of regret -〇/
was prepared. When the reaction test was conducted using this catalyst, the results shown in Table 1 were obtained.

Comparative Example Comparative Example I except that no carbon black was used.
An alumina carrier was produced in the same manner as above. The physical properties of the obtained carrier were as follows.

Staggered strength 3 da to ν specific surface area /10 9 Pore capacity (radius a'y, s~ts; oX > a dak θ
CshiI# (/jtO~3θOOA) 000
111 (3riS~?Sθ00^) θ99
t #modest pore radius giX Next, this carrier trap supports the same th trap palladium as in Example 1,
Finally, catalyst 02 with a palladium loading rate of aOS weight was prepared. When the above reaction test was conducted using this catalyst, the results shown in Roku-ko were obtained.

Comparative Example J Rh@n・-P・・1・n・Alumina carrier 8C8−
Kude (J m/m-bulb) was fired at 10°C. The physical properties of the obtained carrier are as follows.

Specific surface area Ko! nl/ is the pore volume (radius J?j~/j17A) QO4
Il cc/f (/30~JOOOX) Q#
kJ g(,yzt ~tsoooX)ary*
#Modest pore radius 9 da OA Next, palladium was supported in the same manner as in Example No. Catalyst-03 having a palladium loading ratio of OOS and weight was finally prepared. When the reaction test was conducted using this catalyst, the results shown in Table 2 were obtained.

[Brief explanation of drawings]

Figures 1 and 2 are pore distribution state diagrams of the alumina carriers produced in Examples 1 and 2, respectively, where curves No. and 3 are curves showing the state of pore distribution, and curves 1 and 2 are curves showing the state of pore distribution. This is an integration curve of pore volume. Applicant Mitsubishi Chemical Industries, Ltd.

Claims (2)

[Claims] (1) A catalyst comprising palladium supported on a support having a specific surface area of 55 to 120 m2/g, the main component of which is alumina, at least a part of which is a type crystal. The total volume of the radius ate@ to tsoooXO pores is (1*
”-l Oee / f and radius s'xsX
Pore volume and radius from 1soX to 10mm to 5oo
A catalyst for selective hydrogenation, characterized in that both olo and pore volumes are at least alee/f. (2) The O catalyst according to claim 1, wherein the content of palladium is the same as that of the carrier. 3. The catalyst according to claim 1 or 2, which exhibits a pore distribution having one distinct peak at each radius from 301 to 5oooL.