CA1108642A

CA1108642A - Process for improving odor of isopropanol, lower alcohols and other oxy derivatives of lower alcohols

Info

Publication number: CA1108642A
Application number: CA309,212A
Authority: CA
Inventors: Charles Savini
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1977-09-19
Filing date: 1978-08-11
Publication date: 1981-09-08
Also published as: JPS647053B2; GB2004538B; GB2004538A; IT1106918B; FR2403323B1; DE2840118C2; FR2403323A1; NL7809391A; JPS5459207A; DE2840118A1; IT7851114A0

Abstract

ABSTRACT OF THE DISCLOSURE

Methods for deodorizing lower alcohols such as ethanol and isopropyl alcohol and their oxy derivatives such as ethers and eaters are disclosed, including contacting these compounds with a deodorizing contact mass comprising metals and/or metal oxides, preferably of the metals of Group IB, VB, VIB, VIIB, and VIII of the Periodic Table, where the metal oxides are at least partially reduced and the deodorizing contact mass has a minimum particle dimension of greater than about .254 mm so as to be in a form suitable for use in a fixed bed contacting process. In a preferred embodiment, isopropyl alcohol is deodorized employing such deodorizing contact masses, preferably comprising Group VIII metals such as nickel, iron, cobalt and the like, on a support, so that the contact mass has a surface area less than about 1,500m2 per gram.

Description

~8642 1 Methods for deodorizing lower alcohols such as

2 ethanol and isopropyl alcohol and their oxy derivatives such

3 as ethers and esters are disclosed, including ccntacting

4 these compounds with a deodorizing contact mass comprising S metals and/or metal oxides, preferably of the metals of 6 Group IB, VB, VIB, VIIB, and VIII of the Periodic Table, 7 where the metal oxides are at least partially reduced and the deodorizing contact mass has a minimum particle dimension of greater than about .254 mm so as to be in a form suitable 1-' for use in a fixed bed contacting process. In a preferred l' embodiment, isopropyl alcohol is deodorized employing such -~ deodorizing contac~ masses, pref~rably comprising Group VIII
13 metals such as nic~el, iron, cobalt and the like, on z ~' support, so that the contact mass has a surface area less L5 than about 1,500m2 per gram.
~ Overall isopropyl alcohol finishing procedures are l also disclosed employing such deodorizing methods in combina-13 tion with extractive distillation procedures to produce a -- high grade, e.g., 91%, and/or anhydrous grade isopropyl " ,~
- alcohol from a crude isopropyl alcohol stream containing more - than about 0.0005 percent water.

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1 The production and sale of various oxygenated com-2 pounds such as ethers and in particular lower alcohols such as ethanol and isopropylal~ho~ have been hindered by the presence 4 of highly undesirable odors in the commercial products presently being produced. These undesirable odors have been 6 found to be particularly intense and to have caused considerable 7 difficulty in the marketing of these products, which presently 8 have a wide variety of commercial uses. In particular, these 9 commercial uses have included use as solvents, disinfectants, spray products, andin many areaswherethe presence of such odors 11 is of extreme significance, particularly in cosmetics and 12 medicinal formulations-13 This problem is particularly significant with respect 14 to the commercial production of isopropyl alcohol, which in view of its excellent solubility, low toxicity, and cost, has become 16 widely used in such areas as cosmetic products, disinfectants, 17 etc. There has thus been considerable need for commercial pro-18 cesses to deodorize these types of products without unnecessarily 19 hindering the commercial production thereof. Efforts have generally been centered upon processes such as 21 extractive distillation, use of ion exchange resins, adsorption 22 on compounds such as activated charcoal, activated alumina, 23 sand, and the like. In many of these cases the patentees 24 have attempted to analyze the various possible causes of nega-tive odor characteristics in these materials, such as in U.S.
26 Patent No. 2,729,682, assigned to the assignee of the 27 present invention. In the latter patent, the patentee ., . . . " . .:

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1 attempts to overcome the proble~s of "recycle" odor by incor-2 porating into the propylene stream a C4 to C6 monoolefin, 3 followed by water extractive distillation.
4 U.S. Patent No. 2,857,436 teaches the odor improvement of lower alcohols with successive passage of 6 these materials through a bed of unglazed porcelain and a bed 7 of iron metal such as steel wool. None of these prior methods 8 have resulted in a commercially useful and economically 9 attractive method for arriving at products having acceptable odor levels.
11 U.S. Patent No. 2,356,689 teaches a method 12 for the purification of such alcohols employing solid 13 cuprous chloride in specified amounts to stabilize and improve 14 the odor of these alcohols. This method is directed towards the removal of certain small quantities of odor causing 16 impurities. In addition, this method employs the cuprous 17 chloride as part of the alcohol finishing or purification pro-18 cedure-19 U.S. Pa~ent ~o. 2,663,745 discloses a process 20 whereby the quality of various alcohols is improved by 21 intimate contact with small glass particles, i.e., having 22 particle sizes of between about 4 and 20 mesh.
23 The patentee in U.S. Patent No. 2,585,816 teaches the 24 use of such various metals as mercury, copper and nickel for the purpose of improving colors of C4-C12 alcohols produced from 26 C3-Cll olefins via hydroformylation process by essentially 27 reducing the sulfur content therein from, e.g., 58-83 ppm to, 28 e.g., 10-27 ppm~

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1 In a more recent development, Japanese Patent No.
2 51-1684 discloses another method for purifying isopropyl 3 alcohol comprising contacting the alcohol with various Raney 4 metals, including Raney nickel. This method includes contact-ing with the Raney metal, preferably in the presence of a re-6 ducing gas such as hydrogen. The Raney metals are present in 7 amounts of from about .01 to 5 parts per hundred parts of 8 alcohol. This procedure is not commercially feasible, ho~ever, 9 particularly due to the fact that the Raney metals are extremely unstable and potentially dangerous to use.
11 The search has therefore continued for new methods 12 for deodorizing lower alcohols, i.e., C2 and C3 alcohols such 13 as isopropyl alcohol, and their ether and ester derivatives such 14 as diethyl ether in a commercially acceptable and simple manner.
It has now been unexpectedly discovered that said 16 lower alcohols and their oxygenated derivatives can be deodorized 17 to a highly significant extent in a simple, economical 18 and adaptable manner by contacting these compounds with 19 a deodorizing contact mass comprising a metal and/or a metal oxide which is at least partially reduced, the deodorizing 21 contact mass having a suitable dimension, e.g., a particle 22 dimension of greater than about one-hundredth (1/100) 23 of an inch so that it can be effectively employed in a 24 fixed bed contacting process. That is, these particle sizes permit the deodoriæing contact mass to be used in a 26 column and to support itself sufficiently therein to be useful 27 in such fixed bed contacting processes.

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~ 36~2 1 It is therefore necessary that the deodorizing con-2 tact mass have such a minimum particle dimension, e.g., 3 greater than about .254 mm (1/100 inch), preferably greater 4 than about .7~4 mm ~1/32 inch), and most preferably greater than about 1.588 mm (1/6 inch).
6 In a preferred embodiment, the deodorizing contact 7 mass has an effective surface area of less than about 1,500m2 8 per gram, and most preferably the deodorizing contact mass 9 comprises one or more of the metals or metal oxide compounds discussed above incorporated in a porous support. The sup-11 ports used will preferably have a surface area of between 12 about 1 and 1,000 m2 per gram.
13 The deodorizing contact mass may comprise either a 14 metal or a metal oxide of the metals of Groups IB, IIB, IVB, VB, VIB, VIIB, and VIII of the Periodic Table, preferably 16 Groups IB, VB, VIB, VIIB, and VIII, and most preferably 17 Groups IB, VIB, and VIII.
18 A highly deodorized, commercially acceptable 19 stream of isopropyl alcohol can be produced by con-tacting a stream of isopropyl alcohol with such deodorizing 21 contact masses. Preferably, an initial stream of isopropyl 22 alcohol containing from about 0.0005 to 90 percent water is 23 contacted with the deodorizing contact masses in a finishing 24 procedure, so that ultimatelv a deodorized stream of isopropyl alcohol is produced, preferably containing less than about 0.01 26 percent water.

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'` 1, 1 In a preferred embodiment of this aspect of the present 2 invention, the finishing procedure for preparation of isopropyl 3 alcohol includes various extractive distillation steps, in-4 cluding a first distillation step in a tower maintained at a temperature such that undesirable impurities are removed over-6 head, and a bottoms stream of isopropyl alcohol is prepared 7 containing from about 60 to 9~ percent water. Furthermore, the preferred isopropyl alcohol finishing procedure will also include a second distillation step at a temperature of from 10 about 75 to 150C., wherein an improved isopropyl alcohol 11 stream containing from 9 to 15 percent water is removed over-12 head. Finally, it is most highly preferred that this finishing 13 procedure include a third distillation step conducted at a 14 temperature of from about 75 to 150C,, in which the finished isopropyl alcohol stream is removed as bottoms, which includes 16 from 9 to 15 percent water, while various undesirable lower 17 boiling components are removed overhead.
18 In these preferred finishing procedures for the production 19 of isopropyl alcohol, the contacting step of the present in-vention with a deodorizing contact mass may be carried out at 21 any stage, but preferably either prior to or subsequent to the 22 third distillation step.
23 ` ~he following detailed description of the present invention 2~ may more readily be understood by reference to the drawings, wherein;

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, - -1 Figure 1 comprises a schematic dia~ram of a process scheme 2 for production of isopropyl alcohol incorporating the present 3 invention;
4 Figure 2 comprises a schematic diagram of an alternative pro~ess scheme for such production of isopropyl alcohol, and 6 Figure 3 shows the odor/sul~ur content relationship in isopropyl ~ alcohol.
8 One important aspect of the present invention ls 9 1 that it represent8 a simple, economically desirable 10 i efficient method for incorporation into conventional processing 11 techniques for the production of various oxygenated compounds 12 whlch will not disrupt the commercial production of these mat-13 erials, but will lend itself to adaptation to these processes 14 so that final products can be produced having excellent odor properties. In a~ditibn, the deodorizing contact mass employed 16 in this invention can be utilized at various conditions and 17 can be continuously contacted with the stream to be deodorized 18 for extremely long periods of time without the need for regen-19 eration or the like. The contacting procedure utilized is relatively simple, and primarily only results in the deodorizing 21 of the stream without any serious side effects and/or 22 alterations to that stream.
23 With particular reference to prior systems such as 24 that of Japanese Patent No. 51-1684 employing Raney metals for odor improvement of isopropyl alcohol, the present in-26 vention has a number of advanta~es. First, sig-27 nificantly lower yield loss during product purificatiGn can be 28 realized due to the far lower selectivity to undesired byproducts.
29 Also, higher metal treatment capacities, elimination of metal . -: - , , 1 contaminants in the product without the need for costly filtra-2 tion and/or distillation techniques, significantly lower resi-3 dence time, elimination of objectionable waste stre~ms with con-4 sequent clear ecological advantages, elimination of the need for adding hydrogen during treatment, and overall lower costs 6 are also associated with this invention.
7 The lower alcohols to be treated contain relatively small 8 quantities of sulfur-containing impurities, typically below 9 about 100 parts per billion.
The deodorizing contact mass should be suitable for use 11 in a fixed bed or fluidized bed contact process. In particu-12 lar, the deodorizing contact mass should have the particular 13 minimMm particle dimensions set forth above, and furthermore 14 have an effective surface area of less than about 1,500m2 per gram, pre~erably less than about 1,000m2 per gram, and 16 most preferably between about 1 and 500 m2 per gram.
17 One method of obtaining such deodorizing contact masses 18 having such surface areas is to incorporate the metals or at 'eas 19 partially reduced metal oxides in an effective porous support material. Such incorporation may be accomplished by various 21 techniques known in the art, such as impregnation, ion exchange, 22 simultaneous precipitation and/or coprecipitation, or by in-23 corporation of suitable surface stabilizing elements into a 24 massive metal/metal oxide structure, or by any other technique which results in highly dispersed metal/metal oxide surfaces.
26 These support materials themselves can be of various types, in-27 cluding silica, alumina, silica/alumina, zeolites, diatomaceous 28 earth, carbon, various clays, refractory oxides, anc7 the like.

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1 A number of such specific support materials and their 2 surface area and pore volume characteristics are shown in 3 Table I:

Cumulative 6 Surf~c~ Area Pore Volume 7 Support Material !m~/gm) _ (cc/gm) .
8 Porous silica gels 200-700 0.6-0.8 9 Compounded fused silica 40-60 ~ 0.3 Activated alumina (Alorico) 175 ~ 0.4 11 Activated gamma-alumina 220 ~ 0.4 12 Alpha-alumina 10 ~ 0.1 13 Silica/alumina 200-700 0.2-0.7 14 Silica/magnesia 330-630 0.3-0.5 Activated carbons 500-1500 0.6-0.8 16 Activated clays 150-225 0.4_0.5 17 Kiese]quhr (Celite 296) 4-5 1-1.2 18 Porous porcelain 1-2 0.1-0.2 19 In particular, metals and/or metal oxides of Groups IB, IIB, IVB, VB, VIB, VIIB, and VIII of the Periodic Table are 21 utilized, preferably Group IB metals, such as silver 22 and gold, preferably copper, Group IIB metals such as 23 cadmium and mercury, preferably zinc, Group VB metals 24 such as niobium and tantalum, preferably vanadium, Group VIB metals, such as chromium and tungsten, prefer~
26 ably molybdenum, Group VIIB metals, such asrhenium, pre-27 ferably manganese, and Group VIII metals, such as ruthenium, 28 iridium and osmium, preferably rhodium, nickel, platinum, 29 cobalt, iron, palladium and combinations thereof. i.g., Rh/Ni.
Among the most preferred deodorizing contact masses are 31 certain commercially available hydrogenation catalysts which, 32 however, are employed under the conditions of the present 33 invention and do not act as conventional catalysts. These 34 include such commercial hydrofining, hydrogenation, dehydro-.. . :.-:. : . :

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1 genation, oxidation, ammonia synthesis and dissociation, 2 reforming, hydrotreating and gas purification catalys~ (in 3 reduced or activated form) as those so7 d by Girdler, W. R~
4 Grace, Calsicat and Engelhard.
The deodorizing contact mass is preferably employed in a 6 fixed bed contacting tower. The materials will thus be con-7 tacted, preferably in a downflow manner, with the feed 8 stream to be deodorized. Such contacting will suitably be 9 carried out at a temperature of between 50 an~l 300C., preferably between 60 and 150~C., and most preferably 11 between 60 to 120C., and at a pressure generally between 12 about 0 and 400 psig, preferably from 0.5 to 250 psig, and 13 most prefera~ly from about l to 150 psig. With respect to 14 these conditions, however, as discussed above, conditicns can be selected which are the least sèvere possible, and which are 16 most compatible with the particular process scheme with which 17 the present method is to be empl~yed. Finally, the contacting 18 can be carried out at space velocities of between about 0 2 and 19 50 v/hr/v, preferably bet~reen about 0.5 and 35 v/hr/v, and most preferably between 1 and 24 v/hr/v.
21 The present invention can be more fully understood with 22 reference to Figures 1, 2 and 3 hereof. These figures show the 23 method of the present invention incorporated in a conven-24 tional isopropyl alcohol finishing scheme; and also the odor/
sùlfur content relationship in isopropyl alcohol is illus~rated.
26 With reference to the first t~o figures herein, wherein 27 like numerals refer to like portions thereof, Figure 1 repre-28 sents such an isopropyl alcohol processing and deo~orizing 29 scheme.

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l Thus, referring to Figure l, a crude feed stream is fed 2 into extractive distillation tower 2 through line 4. This 3 feed stream generally comprises isopropyl alcohol and fro~
4 about 35 to 55 weight percent water, as well as other impurities, such as isopropyl ether. Water is fed into tower 2 thrDugh 6 line 6, and steam through line 8. In tower 2, which is main-7 tained at a temperature of between about 50 and 150C., prefer-8 ably from 80 to 130C., and at a pressure of from 0 to 20 psig, 9 preferably from 5 to 15 psig, the undesirable impurities are removed overhead through line lO. These impurities in-ll clude various ethers, as well as other such undesirable com-12 ponents. The thus refined isopropyl alcohol stream, again 13 containing between about 40 to 90 percent water, preferably 14 betw~n about 60 to 90 percent water, is withdrawn as bottoms through line 12 and carried to tower 14 for further distillation.
16 In tower 14, generally referred to as the alcohol tower, the 17 isopropyl alcohol stream is further concentrated by removing 18 water as bottoms through line 16. This is accomplished by 19 maintaining this tower 14 at a temperature of between about 75 and 150C., preferably of between about 80 and 120C., and a 21 pressure of between about 0 and 20 psig, preferably of between 22 about 5 and 15 psig. The isopropyl alcohol/water mixture, now 23 containing from about 9 to lS weight percent water is thus 24 withdrawn overhead through line 18, and heavy impurities are purged through line 45. The isopropyl alcohol/water mix-26 ture could thus, in the conventional manner, be carried by 27 lines 20 and 22 to a further distillation column 24, or as - . . ...................... ...

., ., .. . . ".. .:.~ -1 shown in Figure 2 directly through line 18 to such a tower 24, 2 generally referred to as the acetone tower, wherein any ketones 3 such as acetone can be removed overhead as light ends. In 4 accordance with the present invention, line 20 may be closed partially or completely, as desired, by valve means, whereby 6 at least part of the isopropyl alcohol solution removed from 7 tower 14 can be carried through line 26 into the deodorizing 8 tower 28 of the present invention in which the 9 fixed bed catalyst discussed above is maintaine~, so that the isopropyl alcohol/water mixture passes thereover, at the con-11 ditions discussed above. The deodorized and substantially 12 improved isopropyl alcohol/water stream thus obtained is 13 withdrawn from tower 28 through line 30 and can then pass through 14 line 22 into acetone tower 24. Acetone tower 24 is main-tained at a temperature of between about 70 and 120C., prefer-16 ably from 75 to 110C,, and at a pressure between about 0 and 17 20 psiq, PreferablY from S to l~ psig. In this manner, the 18 acetone and/or other ketones and lighter impurities contained 19 in the isopropyl alcohol mixture can be withdrawn overhead through line 32, while a prime grade isopropyl alcohol stream 21 is withdrawn from the bottom of tower 24 through line 34. This 22 material generally comprises the azeotrope, contàining ~boùt 23 91 percent isopropyl alcohol in water. The overhead withdrawn 24 from line 32 including acetone, some isopropyl alcohol, and some water is principally a reject stream from acetone tower 24.
26 The prime grade isopropyl alcohol withdrawn as bottoms through 27 line 34 from tower 24 can be further finished by a dehydration , 1 process to produce greater than 99 percent isopropyl alcohol 2 therefrom.
3 With specific reference to Figure 2, it can be seen that 4 the feed withdrawn overhead from tower 14 through line 18, and

5 again containing isopropyl alcohol containing from about 9 to

6 15 percent water, is fed directly to acetone tower 24 for

7 further distillation. This tower operates in the manner des-

8 cribed above with respect to acetone tower 24 in the scheme

9 of Figure l. However, in this case, ~he deodorizing tower 28 of the present invention is located downstream from tower 24 11 so that the prime grade isopropyl alcohol product withdrawn 12 from tower 24 through line 34, instead of passing directly 13 out of the process through line 36, can be forwarded through 14 line 38 into tower 28 for contactwi~ the deodorizing mass of the present invention. The deodorized stream can then be with-16 drawn through line 40 and line 36.
17 With regard ^to Figure 3, it can be seen that a low 18 level of sulfur present in an isopropanol sample does not 19 necessarily mean a lower level of odor detected in the sample. This suggests that the odor-causing impurities present 21 in lower alcohols may be more than simple sulfur compounds; and 22 also that the deodorizing metals or metal oxides employed in 23 the instant invention may serve a different process from tha~
24 which has been ~nown in the prior art.
Although the flow plans shown in Figures 1 and 2 are ex-26 emplary of certain embodiments of the present invention, it will 27 be appreciated that the deodorizing tower can be located in . .
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1 many different locations throughout an iso~ropyl alcohol fin-2 ishing plant, particularly since it is so highly adaptable 3 to various conditions of temperature, pressure, space velocity, 4 stream compositions, etc., and furthermore since it can be used over extended periods of time and not result in the dis-6 ruption of the process streams.

7 The present invention can be more fully understood with 8 reference to the following examples.

Three hundred ml of a 91% isopropyl alcohol product 11 having a 12+ RHB (non-saleable, off-specification ma,erial) was 12 heat soaked in a 500 ml flask with thirty (30) gm of 1/8 13 inch tablets of activated ENCAR hydrogenation catalyst having 14 the following characteristics:
Type: Co-precipitated nickel-copper-silica-kieselguhr 16 catalyst 17 Ni content: 45 wt. %

18 Cu content: 4.5wt. ~
19 BET surface area: 250 m /gm Apparent bulk density: 53 lb/ft3 21 Crush strength: 7 lb (l/8 x 1/8 inch tablet) 22 Cumulative pore volume: ~ 0.35 cc/gm 23 Contacting at atmospheric pressure and at atempera~e of about 24 78C. was carried on for about 2 hours. The resultant 25 isopropyl alcohol was evaluated by an Odor Panel. The 26 product was judged to be comparable to cosmetic quality alcohol 27 and to be free from recycle odor. The results are included in 28 Table II below.

2 Seventy-two gm of a commercial hydrogenation catalyst 3 sold by Harshaw as Harshaw Ni-0104T-1/8 hydrogenation catalyst 4 having the following characteristics:
Type: Nickel on kieselguhr 6 Ni content: 58 wt. %
7 BET surface area: 160 m2/gm 8 Apparent bulk density: 90 lb/ft3 9 Crush.strength.: 9 lb ~1/8 x 1/8 inch tablet) Cumulative pore volume: ~ 0.20 cc/gm 11 was contacted with 300 ml of a 91% isopropyl alcohol 12 product having a 12+ RHB odor class in a 500 ml flask.
13 The temperature of this system was maintained at about 80C for 3 14 hours at atmosph.eric pressure The resultant isopropyl alcohol was rated by an Odor Pane~. and the results are 16 included in T.~ble II. This product was judged to be of 17 cosmetic quality and free from recycle odor.

19 Fifty-six gm of a commercial h~drogenation 20 catalyst sold as Harshaw Ni-3250 T-1~8 hydrogenation cata-21 lyst having the ~ollowing characteristics:
22 Type: Nickel on support 23 Ni content: 52 ~t %
24 BET surface are; 1~5 m2/gm . Apparent bulk density: 68-69 1~/ft3 26 Crush strength: ~ 18 lbs ~1/8 .x 1/8 inch tablet) 27 Cumulative pore yolume: ~ ~.32 cc/gm ~:, : ~: : ::, ; ~:. : .~ .. .-1 was heat soaked in 30~ ml of a 91% isopropyl alcohol 2 product having a 12+ RHB odor class in a 500ml flask 3 ~or three hours at a temperature ofabouL 80C. at atmospheric 4 pressure. The resultant isopropyl alcohol stream was rated by an Odor Panel, and the results are included in Table II.
6 This product was judged to be of cosmetic quality and free 7 from recycle odor.
8 ExAMpLEs 4-7 9 The procedure of Example 3 was duplicated in four succes-sive runs, except that the same Harshaw Ni-3250 T-1/8 hydrogena-11 tion catalyst was re-used in each run. In each case the resultant 12 isopropyl alcohol was rated by the Odor Panel, and the 13 results included in Table II. These products were 14 again judged to be of cosmetic quality and free from recycle odor, thus demonstrating that effectiveness of the deodorizing 16 mass during successive product treatments was not reduced.

.
18 Odor Evaluation by Odor Panelists 19 ODOR RATINGl Product Quality Relative to 21 Example No. FeedProduct Cosmetic Grade 22 i 12+RHB 2 Equivalent 23 2 12+RHB 2+ Comparable, but not as good 24 3 12+RHB ~2 Equal or better 25 4 - 7 12~RHB c2 Equal or better 26 Cosmetic Grade 2 228 (Control) -lIsopropyl alcohol odor class rating scale 31 Lowest Intensity - Odor Class 2 32 Highest Intensity - Odor Class 12 33 Suffix indicates odor type, e.g. "R" designates 34 recycle odor, "HB" designates high boiler odor ., ~ : ., , . , . ., - ~, ................... ..
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2 In order to compare the present process with that of 3 Japanese Patent No. Sl-1684 the odor improvement of isopropyl 4 alcohol in a post treatment deodorization process was carried out under comparable conditions with a nickel supported con-6 tacting mass in accordance with the'present invention (a com-7 mercial Harshaw Ni-3250T supported nickel hydrogenation cata-8 lyst) and with Raney nickel. The results obtained are sum-9 marized in Table ~II below. In addition to those results, it

10' is also noted that the process of the present invention, as

11 compared to that of the ~apanese patent, does not require

12 product filtration or distillation after treatment, raises

13 no catalyst separation or waste stream disposal problem and

14 does not require the use of hydrogen therein.
~XAMPLE 9 16 A 91% isopropyl alcohol stream having a 12+RHB odor class 17 was pumped continuously through a two inch diameter pipe filled 18 with commercial Harshaw Ni-3250T'hydrogenation catalyst. Flow 19 rates,of from about 1 to 24 volumes of the isopropyl alcohol per hour per volume of nickel contacting mass were employed, 21 as well as temperatures of from 55 to 85C., and pressures from 22 atmospheric to about 250psig. The treated isopropyl alcohol 23 product was mar]cedly improved in odor quality, from a bad odor 24 feed to a product similar to cosmetic grade. The product fur-thermore did not contain measurable amounts of residual metals, 26 and the bed was still effective after more than 10,000 volumes 27 of isopropyl alcohol per volume of nickel contacting mass had 28 been processed therein.

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-~ 2 ~ EXAMPLES 10 16 2 About 300 ml of a 91% isopropyl alcohol having 3 a 12+ RHB odor class was treated in a 500 ml flask frr 4 about 3 hours at a temperature of about 80C. under atmospheric s pressure by employing about 15 gm of a series of different 6 deodorizing metals described in Table IV below. The resultant 7 isopropyl alcohol stream was rated by an Odor Panel and judged 8 to be free of recycle-type odor and suitable for odor sensitive 9 end uses.
TABLE IV
11 APPLICABILITY OF VARIOUS ~TALS AS DEODORIZING AGENT FOR

13 Example No. Deodorizing Agent 14 10 0~5~/o Pt/A12O3 11 0.5% Rh/A12O3 16 12 0.5~/0 Ru/A1203 17 13 0.5% Pd/A1203 18 14 10% Fe/1% Cu/~1203 19 15 50% Co/Refractory Oxide Support 16 6% Ni/l9~W/Al2o3 22 A 91% isopropyl alcohol stream having a 12+ RHB odor 23 class was pumped through a 1/2 inch tube filled with 25 cc of 24 Ni-3250T-1/8 catalyst at a space velocity of 4.0 v/hr/v 25 &t stmospheric pressure and a temperature of about 8QC. The 26 treated isopropyl alcohol was judged by an Odor Panel to be 27 markedly improved in odor quality with all objectionable-type 28 odors being removed and considered to be suitable for low ~ odor-type alcohol end uses.
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2 The same 91% isopropyl alcohol stream of 12+ RHB odor 3 class W5S pumped through a 1~2 inch tube filled with e~ual volumes 4 o~ Ni-3250T-1/8 catalyst and 0.5% Rh/A12O3 T-1/8 catalyst placed in the reactor tube such that the nickel catalyst con-6 tacted the alcohol before the rhodium catalyst. The odor 7 treatment conditions employed were identical to those used in 8 Example 17A. The product alcohol was judged by the Odor Panel 9 to be of superior odor quality to the purified alcohol produced 10 in Example 17A.

12 A series of untreated isopropanol samples were first 13 analyzed by employing a Houston Atlas Sulfur Analyzer marketed 14 by Xouston Atlas, Inc. in order to determine their sulfur con-

15 tent; and subsequently were subjected to odor evaluation

16 by an Odor Panel for the purpose of determining whether or

17 not there exists a functional relationship between the sulfur

18 content and the level of objectionable odor detected in the

19 isopropanol samples. The results are plotted on Figure 3;

20 and it was concluded that there does not exist a direct relation-

21 ship between the two.

22 The foregoing description of the invention and specific

23 embodiments are for the purposes of illustration only, and

24 not for limitation of the invention. It is to be understood

25 that the invention is not to be limited by any theory or illus-

26 tration presented, but only by the following claims.

. ~

Claims

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

1. A method for deodorizing a C2 or C3 alcohol which comprises contacting the alcohol with a deodorizing contact mass consisting of a metal or a metal oxide incorp-orated in a porous support, the metal oxide being partially reduced to metal, and wherein the deodorizing contact mass has a minimum particle dimension of greater than 0.254 mm so as to be in a form capable of being used in a fixed bed contacting procedure.

2. The method as claimed in claim 1 wherein said metals and metal oxides comprise metals selected from the group consisting of Groups IB, IIB, IVB, VB, VIB, VIIB and VIII of the Periodic Table.

3. The method as claimed in claim 2 wherein said metals and metal oxides comprise a metal selected from the group con-sisting of Groups IB, VIB and VIII of the Periodic Table.

4. The method as claimed in claim 2 wherein said metal is selected from the group consisting of nickel, cobalt, iron, palladium, rhodium, ruthenium, platinum, iridium, osmium, tungsten, copper and mixtures thereof.

5. The method as claimed in claims 1, 2 or 3 wherein said deodorizing contact mass has an effective surface area of less than about 1,500 m2/gram.

6. The method as claimed in claim 1 wherein said deodorizing contact mass comprises said metal incorporated in a porous support.

7. The method as claimed in claim 6 wherein said porous support is selected from the group consisting of silica, alumina, silica/alumina, carbon, clays, zeolites, refractory oxides, and mixtures thereof.

8. The method as claimed in claim 6 or 7 wherein said porous support has an effective surface area of between about 1 and 1,000 m2/gram.

9. The method as claimed in claim 1 wherein a stream of isopropyl alcohol and water is contacted with the deodorizing contact mass.

10. The method as claimed in claim 9 wherein the stream contains from about 0.0005 to 90 weight percent water.

11. The method as claimed in claim 10 wherein the isopropyl alcohol and water is the product stream from an alcohol dehydration process.

12. The method as claimed in claim 9 including distilling a stream of isopropyl alcohol in a first tower at a temperature of between about 80 and 130°C, and a pres-sure of between about 5 and 15 psig, so as to produce a liquid stream of isopropyl alcohol from the bottom of said first tower, containing between about 40 and 90 weight perdent water, and to produce an overhead vapor stream from said first tower containing undesirable impurities.

13. The method as claimed in claim 12 including distilling said liquid stream of isopropyl alcohol containing about 40 and 90 weight percent water in a second tower at a temperature of between about 80 and 120°C, and a pressure of from about 5 to 15 psig, so as to produce a highly concen-trated liquid stream of isopropyl alcohol from the top of said second tower, said stream containing between about 9 and 15 percent water, a bottom stream from said tower com-prising water, and a side stream from said tower comprising heavy impurities.

14. The method as claimed in claim 13 including condensing an overhead vapor stream comprising isopropyl from the second tower to produce the stream containing between 9 and 15 percent water, and distilling said isopropyl alcohol stream in a third tower maintained at a temperature of between 75 and 110°C, and a pressure between 5 and 15 psig, so as to remove a highly purified isopropyl alcohol stream in a liquid state from the bottom of said third tower, said stream containing between about 9 and 15 percent water, and an overhead vapor stream from said third tower compris-ing light impurities.

15. The method as claimed in claim 14 wherein con-tacting with said deodorizing contact mass is carried out with said overhead stream of isopropyl alcohol withdrawn from said second tower.

16. The method as claimed in claim 14 wherein the deodorizing contact mass is contacted with the liquid stream withdrawn from the bottom of the tower.