CA1080685A

CA1080685A - Catalyst activation process

Info

Publication number: CA1080685A
Application number: CA269,936A
Authority: CA
Inventors: James L. Carter; John H. Sinfelt
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1976-02-02
Filing date: 1977-01-18
Publication date: 1980-07-01
Also published as: IT1080316B; AU514928B2; BR7700626A; JPS5294890A; GB1574389A; NL7701077A; FR2339432B1; AU2149477A; BE850966A; FR2339432A1; JPS5939182B2; DE2702327A1; DE2702327C2

Abstract

ABSTRACT OF DISCLOSURE

The invention relates to a process for activating catalysts, preferably a massive nickel catalyst, comprising copper, nickel and silica and being characterized as having a nickel surface area of from 50 to 100 m2/g and a total surface area of from 150 to 300 m2/g, comprising the steps of (1) reducing said composite at a temperature and for a time sufficient to yield a partially activated catalyst composite, (2) contacting said partially activated catalyst composite with a feed which undergoes exothermic exothermic reaction in the presence of said partially activated catalyst composite which include a temperature greater than step (1), whereby the temperature at the catalyst surface exceeds the temperature of the catalyst bed and continuing said contacting for a time sufficient to convert said partially activated catalyst composite to a high activity catalyst composite.

Description

lO~Of~

2 The instant invention relates to a process for

3 activating catalysts which are activated by reducing at

4 elevated temperatures. The catalysts are preferably massive nickel catalysts, comprising nickel and silica most pref-6 erably also copper and being characterized as having a 7 nickel surface area of from 50 to lOO m2/g and a total 8 surface area of from 150 to 300 m2/g, said catalysts being 9 prepared by a process comprising the step of contacting a porous support with a solution containing nickel9 copper 11 and silicate ions, at conditions whereby said ions are co-12 precipitated onto said support to yield a composite com-13 prising nickel, copper and silica precursors on said porous 4 support.
BACKGROUND OF THE PRIOR ART
16 Massive nickel hydrogenation catalysts having high ~-17 nickel surface areas, for example, more than 70 m2/g, are 18 known in the art. U.S. Patent 3,868,332 teaches such a 19 catalyst characterized as having a low sodium content3 i.e. 9 less than 0.2 wt. % based on total weight of catalyst. In 21 U.S. Patent 3,859,370 the use of this catalyst in hydrogen~
22 ation processes is claimed.

24 This invention relates to a process for the activation of catalysts which are activated at elevated 26 temperatures in the presence of a reducing gas, preferably D nickel-silica catalysts which contain (preferably) very 28 small amounts of alkaline impurities. In a preferred 29 embodiment this catalyst additionally comprises copper.
The instant invention relates to an improved 10~0~

1 method for activating cntalysts which are commonly scti-2 vated by red~ction at elevated temperatures, for example, 3 at least 150Co The catalyst prior to this activation step 4 may be prepared by any method known in the art. For example, in preparing a supported catalyst which comprises 6 a metal supported on an inert, porous support, a catalyst 7 metal precursor will be impregnated or precipitated onto 8 the support or, alternatively, the supported catalyst may 9 be formed by coprecipitation9 from solution9 of the precur-lo sors of both the metal and the support. The solution may 1 comprise any solvent in which the catalyst metal precursors 12 are soluble, i.e., the solvent may be aqueous or nonaqueous.
13 The excess solvent will be removed by methods known in the 14 art, including heating and/or use of ~ v~cuum. After solvent removal, if desirable, a calcinatiGn in air or an 16 inert gas may be carried out.
17 The improved process of the instant invention is 18 especially suitable for preparing hydrogenation catalysts 19 which are activated by reduction at high temperature. Most especially, the process of the instant invention is useful 21 for activating the massi~enickel hydrogenation catalysts 22 described in the hereinabove referred to patents. In its 23 most preferred embodiment, the process of the instant 24 invention is utilized to activate the catalysts which comprise nickel, copper and silica coprecipitated onto a 26 porous support which may be particulate.
27 In one preferred embodiment, the importance of 28 the instant invention resides in the fact that many 29 commercial hydrogenation units are limited to a maximum ~ temperature at the inlet of about 200C to 250C. It is lO~V~

~ noted that there are commercial hydrogenat~on units wherein 2 a furnace is used to preheat the feed at the inlet, however 3 these units must be designed for tempe~atures of from 350C
4 to 400C, since the nickel silica catalyst must be reduced at a temperature of at least about 350C for complete 6 activation. Thus the catalyst is generally reduced and 7 stabilized by the manufacturer. T~is requirement, however, 8 increases the cost of the catalyst and makes in situ 9 activation more attractive. Because of the above limitation 10 on inlet temperature, prior to the discovery of the process -11 of the instant invention, in situ techniques were not 12 commonly available to the commercial users of nickelosilica 13 hydrogenation catalysts.
14 In a preferred embodiment of the process of the instant invention the massive nickel catalyst 9 which is a 16 high surface ares nickel catalyst preferably eonta;ning 17 copper, is charged into the hydrogenation reactor in a 18 manner designed to minimize absorption of water from the 19 atmosphere. The reactor may be purged with dry air or a ~ dry inert gas to remove traces of water from bo~h the 21 reactor and the catalyst. The reactor is closed and then 22 purged with an inert gas to remove oxygen~ When the oxygen 23 level is sufficiently low, i.e. less than 1%, the purge 24 gas is terminated and a reducing gaS9 preferAbly a hydrogen~
rich gas is passed over the catalyst at a flow rate of from 26 l,000 V/Hr/V to 509000 V/Hr/V, preferably 5~000 V/Hr/V. The 27 reducing gas iS bled into the reactor with steadily in- -28 creasing flow up until the point where full flow has been 29 obtained. Then the temperature at the inlet is increased in increments of 10C to 30C at thirty minute intervals 10~

1 until a temperature of from 210 to less than 235C is 2 achieved within the catalyst bed. This temperature is 3 maintained for a time sufficient to provide a partially 4 activated catalyst composite9 i.e. 9 with 10~75~/o of the S activity of a fully activated catalyst. The catalyst at 6 this point is an active cstalyst, although9 due to the 7 fact that much of the nickel exists in the nonmetallic 8 (noncatalytically active) state, the catalyst is charac~
9 terized as being partially activatedO However9 as will 0 be further described below9 it is critical ~hat suffi~ient 11 nickel exist in the metallic 9 iOe. catalyticaliy active 12 state to yield a composite having some catalytic activity.
13 The temperature at the inlet is then l~wered to from ~bout 14 100C to 125C and the flow of a reactive feed through the catalyst bed is commenced. The reactive feed when a 16 hydrogenation catalyst is being activated by the process 17 of the instant invention is conveniently an unsaturAted 18 hydrocarbon, i.e.~ either an aromati~ or olefinic hydro~
19 carbon; or oacygenated derivatives thereof9 eOgO alcohols9 ~ ethers, etc. Examples of reactive feed which sre useful 21 in the process of the instant invention includeo C2 to ~ -22 C20 olefins, C6 to C20 aromatic hydrocarbons9 e.g. benzene9 23 toluene, xylene~ hexene 9 butadiene~ styrene 3 etc. The 24 reactive feed may be 100% olefinic or aromatic or comprise mixtures of olefins and aromatics. Nonreactive comp~nents 26 such as paraffins may also make up a portion of the 27 reactive feedstream. Hydrogen is provided with the 28 reactive feed since it is necessary as a reactant and to 29 reduce the nickel to the metal. It is critical to tSe ~ process of the instant invention thst the reaction used to 10~0~

1 activate the partially activated catalyst composite must be 2 exothermic since the purpose in contacting the catalyst 3 with a reactive feed, at this point, is to utilize the 4 heat of reaction to obtain a higher temperature at the surface of the catalyst than is available at the inlet or 6 in the catalyst bed. Thus, the skilled artisan would 7 adjust the reactive feed accordingly to obtain sufficient 8 heat of reaction to convert the partially activated catalyst 9 into a high activity catalyst, i.e., a catalyst with more lo than 75% of the activity of a fully activated catalyst.
11 The temperature during the contacting of the 12 partially activated massive nickel hydrogenation catalyst 13 with the reactive feed is raised 9 in increments of 10C to 14 30C per thirty minute interval9 until the maximum temperature in the catalyst bed exceeds 235C9 preferably 16 the temperature is raised to between 235C and 275C.
17 The ratio of the reactive feed to hydrogen and 18 flow rates of both are adjusted to achieve a sufficient 19 exotherm to raise the temperature of the catalyst in the bed to a level of about 2500275C or more. The catalyst 21 will be maintained at this temperature by means of the 22 reaction occurring for a time sufficient to achieve9 23 preferably full, i.e., 100%, activation of the catalyst, 24 approximately 2 to 20 hours.
The massive nickel catalyst activated by the 26 process of the instant invention are useful in hydrogena~
27 tion and may be used to hydrogenate aromatics, aldehydes, 28 alcohols, olefins, including both straight and branched 2g chain, and the various hydrocarbon double bonds found in edible fats and oils~

lO~V~5 2 The following examples best illustrate the process 3 of the instant invention. The catalyst used in all the 4 tests was prepared according to the following method:
8.75 gm. of Cu(NO3)2 3H20 and 112 gm. of Ni(NO3)2-6H20 were 6 dissolved in 500 ml of distilled water, then 38 gm. of 7 Na2SiO3 9H2O was dissolved in another 500 ml of water and 8 5 gm. of acid washed kieselguhr was slurried in this 9 second solution. The second solution with the kieselguhr lo slurried therein was stirred vigorously while the first 11 solution containing the copper and nickel salts was added 12 at a uniform rate over a 20 minute period. This mixture 13 was then heated to the boiling point and 80 gm. of NH4HC03 14 was added at a uniform rate over a 20 minute period. The mixture was kept at the boiling point for 3 hours while 16 stirring continued. It was then filtered and washed 5 17 times with boiling water, each wash consisting of 500 ml 18 of water. The filtercake was then dried at 120C and 19 calcined in air for 4 hours at 400C. The catalyst contained by weight 45.0% nickel, 5.0% copper, and 50% silica (the 21 impurities present in the acid washed kieselguhr being 22 included in the weight of silica given).
23 In Example A the catalyst was sctivated in H2, 24 at a catalyst bed temperature of 245C, with a nonreactive 2s feed flow. In Example B, the catalyst was activated in 26 H2, at a catalyst bed temperature of 245C, with a reactive 27 feed which contained 22~3% aromatics. In Example C, the 28 catalyst was activated in H2, at a catalyst bed temperature 29 of 245C, with a reactive feed which contained 21~77o ~ aromatics. In Example D, the catalyst was activated first iO~V~

1 with H2 at a catalyst bed temperature of 232C, then with a 2reactive feed which contained 21.7% aromatics at 245C.

4 ExamPle A ExamPle B
Conversion of 6 aromatics at 7 100 hours on oil 60% 80%
8 Run Conditions:
9Space Velocity - 10 Volume feed/Hr/Volume 10Catalyst 11 Pressure - 600 psig 12 Temperature - 160C
13 H2 - 1000 Standard Cubic Feet/
14 Barrel Feed - Mineral spirits*
16 22.3% aromatics 18 ExamPle C ExamPle D
19 Conversion of aromatics at 21 75 hours on oil 24% 34%
22 Run Conditions:
23 Space Velocity - 30 Volume feed/Hr/Volume 24 eatalyst Pressure - 600 psig 26 Temperature - 160C
2i H2 - 1000 Standard Cubic Feed/
28 Barrel 29 Feed - Mineral spirits*
21.7Z aromatics 31 *The mineral spirits used was VARSOLTM #3, from 32 Exxon Chem. Co. U.S.A., which i8 a naphtha 33 fraction with a boiling range of 310F to 341F, 34 aromatics content of from about 21 to 23% on a wt. basis and 1.5 ppm sulfur or less.

lO~V~S

1 In Table I, Example B shows significantly higher 2 conversion than Example A. The data in Table II show the 3 added improvement obtained by the activation procedure 4 described in this application. Example D shows substan-tially more conversion than Example C which did not include 6 a treatment with H2 prior to the high temperature activation 7 with the reactive feed. Thus, the data in Tables I and II
8 demonstrate the criticality of the two step activation 9 process of the instant invention.
It should be noted, for purposes of definition, 11 Example D represents a fully active catalyst composite, 12 while Examples A, B and C, represent partially active 13 catalyst composites, i.e., they have an activity (as 14 measured by the reaction described in Example D and defining the catalyst activity of said catalyst composite as 100%) 16 of from 10 to 75%.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for activating a catalyst wherein said catalyst is activated by heating in a reducing atmosphere, which comprises (l) reducing said catalyst by heating the catalyst in the presence of hydrogen at a temperature sufficient to partially activate the catalyst and (2) contacting said partially active catalyst in the presence of hydrogen with a reactant feed which undergoes an exothermic reaction in the presence of said partially activated catalyst at conditions whereby said reaction occurs, said conditions including temperatures at least greater than the temperature at which the catalyst is partially activated and (3) continuing said contacting for a time sufficient to convert said partially activated catalyst to a fully activated catalyst.

2. In a process for activating a massive nickel catalyst, said catalyst com-prising copper, nickel and silica and said catalyst being characterized as having a nickel surface area of from 50 to 100 m2/g and a total surface area of from 150 to 300 m2/g, said catalyst being prepared by contacting a porous support with a solution of nickel, copper and silicate ions at conditions where-by said ions are coprecipitated onto said support to yield a composite com-prising nickel, copper and silica precursors supported on said porous support, the improvement which comprises (l) reducing said composite by heating the composite in the presence of hydrogen at a temperature of less than about 235°C
for a time sufficient to yield a partially activated catalyst composite, (2) contacting a bed comprising said partially activated catalyst composite in the presence of hydrogen and at reaction conditions, said reaction conditions in-cluding a catalyst bed temperature of from about 200°C to 275°C

with a feed which undergoes exothermic reaction in the presence of said partially activated catalyst composite at reaction conditions, whereby the temperature at the catalyst surface exceeds the temperature of the catalyst bed, and continuing said contacting for a time sufficient to convert said partially activated catalyst composite to a high activity catalyst composite.

3. The process of claim 2 wherein said porous support is a particulate support.

4. The process of claim 3 wherein said support is selected from the group consisting of silica and kieselguhr.

5. The process of claim 3 wherein said feed com-prises an unsaturated hydrocarbon or oxygenated-derivative thereof.

6. The process of claim 5 wherein said unsaturated hydrocarbon is a C6 to C20 aromatic hydrocarbon.

7. The process of claim 5 wherein said unsaturated hydrocarbon is C2 to C20 olefinic hydrocarbon.

8. The process of claim 3 wherein step (1) is continued for a time sufficient to yield a catalyst with an activity of from 10 to 75% of the fully activated catalyst.

9. The process of claim 8 wherein step (2) is carried out at conditions sufficient to yield a catalyst with an activity of greater than 75% of the fully activated catalyst.

10. The process of claim 3 wherein said solution is an aqueous solution.