CA1234162A - Process for the production of naphthalene - Google Patents
Process for the production of naphthaleneInfo
- Publication number
- CA1234162A CA1234162A CA000475666A CA475666A CA1234162A CA 1234162 A CA1234162 A CA 1234162A CA 000475666 A CA000475666 A CA 000475666A CA 475666 A CA475666 A CA 475666A CA 1234162 A CA1234162 A CA 1234162A
- Authority
- CA
- Canada
- Prior art keywords
- naphthalene
- clay
- methanol
- colour
- range
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10C—WORKING-UP PITCH, ASPHALT, BITUMEN, TAR; PYROLIGNEOUS ACID
- C10C1/00—Working-up tar
- C10C1/18—Working-up tar by extraction with selective solvents
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/005—Processes comprising at least two steps in series
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/12—Purification; Separation; Use of additives by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/14—Purification; Separation; Use of additives by crystallisation; Purification or separation of the crystals
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Analytical Chemistry (AREA)
- Water Supply & Treatment (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process for producing a refined naphthalene of mothball colour-stable quality made from coal-derived crude naphthalene oil. A large number of stages is avoided, and the process does not require sulfuric acid washing and environmental problems associated with the disposal of acid sludge. The process comprises crystallizing naphthalene from a solution of crude naphthalene in methanol followed by clay treatment to produce refined naphthalene.
A process for producing a refined naphthalene of mothball colour-stable quality made from coal-derived crude naphthalene oil. A large number of stages is avoided, and the process does not require sulfuric acid washing and environmental problems associated with the disposal of acid sludge. The process comprises crystallizing naphthalene from a solution of crude naphthalene in methanol followed by clay treatment to produce refined naphthalene.
Description
~3'~L~6;~
-- 1 ~
PROCESS FOR THE PRODVC~;CON OF NAPH'rHAI,ENE
The invention relates to a process for the pro-duction of refined naphthalene of mothball colour-stable quality from coal-derived crude naphthalene oil.
Naphthalene is a widely used starting raw material for the organic chemical industry. Thus, large quantities of naphthalene are used for the production of phthalic anhydride, for the manufacture of ~C and ~, naphthol and other organic intermediates ~.S. Stobaugh, Hydroc. Processing, Vol. 45, No. 3, P. 149, 1966). Considerable quantities of very pure naphthalene are used for the manufacture of moth-balls.
One method of obtaining naphthalene is by first distilling coal tar and further purifying the distillate boiling between 205 ana 235Co The resulting coal tar fraction which is generally called naphthalene oil, contains naphthalene, methylnaphthalene, phenolic compounds and heterocyclic constituents such as thionaphthene ~G. Gilbert et al, Ind.
Eng. Chem. Vol. 53, No. 12, p.993, 1961) as well as unsaturated compounds such as indene and its alkylated derivatives.
The naphthalene-content of the naphthalene oil generally varies between about 75 - 90%; the quality of the naphthalene oil is usually characterized by its melting point which ranges from about 65 to 75C~ according to the naphthalene content of the naphthalene oil. In order to produce refined naphthalene with a melting point of about 19.6C. the impurities con-tained in a naphthalene oil have 30 to be removed by chemical and physical processes. The extent of the purification depends on the final application of the naphthalene product. Naphthalene for the manufacture of phthalic anhydride usually has a melting point of 78 - 79C.
whereas naph-thalene of moth~all grade has a minimum melting A
..
,.
~3'~6~
point of 80C and in addition, must not discolour upon exposure to air and light.
Because of the importance of this aromatic compound, the purification and isolation of naphthalene from coal tar fractions have been subjècts of considerable attention.
Traditionally refined naphthalene was produced by washing the naphthalene oil wi-th suIfuric acid followed by aqueous sodium hydroxide. Recently, however, crystalliz-ation processes from the melt have gained importance because they can offer advantages in terms of yield and cause no environmental problems associated with the disposal of acid sludge. A typical process for the production of refined naphthalene from the melt is dèscribed by K. Saxer et al, AIChE meeting, ~ov . ~5 ~9, 1979. Thus naphthalene of a purity of at least 99.7 ~ . could be produced in high yield-using six stages and starting from a naphthalene oil which contained already 90% (melting point 74.1C).
Another process based on the principle of melt crystalliæation is described by I.A. Brodie, Mech. Chem. Eng.
TranS. Inst. of Eng. Austr. 1971, page 37 - 44. For this process too~ a highly concentrated naphthalene oil is recommended for the optimum use of this crystallization technology. Preferably, these crystallization technologies are applied when a highly concentrated starting material is available; otherwise yield and efficiency are adversely affected.
However, a small number of tar refineries are in a position to produce naphthalene oil with a melting point of 73C. or higher~ equivalent to a naphthalene content of 87% or higher. Thus it can be advantageous to resort to different refining methods in order to produce naphthalene of high purity.
A further aspect has to be considered in the production of mothball grade naphthalene. Naphthalene usuable 3.6a~;
for the manufacture of mothballs must retain colour stability upon exposure to air and ligh* for a period of at least two weeks; thus the impurities still contained in refined naphthalene have to be removed below a certain threshold le~el. The mechanism of discolouration is not fully understood; it ls, however, generally assumed that unsaturated compounds such as indenes and phenolic con-stituentS have a discolourating effect.
Many attempts have been made in thè past to produce naphthalene of mothball grade in an economic way. Tradition-ally sublimination processes have been used to produce naphthalene of mothball grade, this methodr however, is extremely costly. Other chemical processes have been dascribed in the literature (H.G. Franck and G. Collin, Steinkohlenteer, Springer, 1968J. These processes, however, turned out to be not generally accep-table because of high cost Ihydrogen treatment) or difficuIt process conditions (partial chlor-ination or reaction with FeC13).
British patent 651,514 describes treating naphth-alene with silica ge~. The-silica gel used in this process had to be considerably modified by washing it free of sulfate anions. No indication as to the indene content of the final naphthalene product is disclosed.
Clay treatment of petroleum derived naphthalene is di5closed by R.B. Stobaugh (Hydrocarbon Processing, Vol.
45, No. 3, page 149f 1966) but this cannot be compared with the refining of coal tar derived naphthalene as petroleum derived naphthalene contains markedly different impurities.
The diEficulty of producing colourless naphthalene from coal tar fractions with inorganic adsorbents is additionally documented in a Russian paper (Zh. I. Repina et al, Koks i Khimya~ No. 9, page 27, 1980). Thus it has been a constant challenge for the manufacturer of mothball grade naphthalenè to develop an economic way for ~3~6~
the pr~ductio~ of mothball g~ade naphthalene~ or in other words, to produce refined naphthalene which contains a sufficiently low level of impurities to render' the refined naphthalene colour-stable.
Methanol has been used as a solvent for washing naphthalene crystals crystallized from naphthalene oil.
British patent no. '686,1'66 discloses such a process. However, it has been found that naphthalene having a melting point above80C. produced by methanol washing of naphthalene crystals in a limited number of stages, discolours upon exposure to light and air. According to the prior art it is not possible to make a colour~stable naphthalene by this method. (H.G. Franck, G. Collin,'Steinkohlenteer~ ~pringer, Page 70, 1968; and G. Gilbert,'Ind. Eng. Chem., Vol. 53, No. 12 r Page 993, 1961).
Likewise the prior art indicates that a refined naphthalene having a melting point above 79.6C. discolours if the materiaI is produced by crystallization from the melt in a limited number of stages or by the traditional refining process wlthou-t using sulfuric acid and caustic soda.
Surprisinglyt 'a novel method has been found for the production of naphthalene of mothball quality which can be performed in a very economic way, additionally, this novel process is very versatile as to the naphthalene con-tent of thè star-ting naphthalene oil fraction.
It has been found that by dissolving naphthalene oil distilled from coal tar, in methanol, preferably at a naphthalene to methanol ratio in the range of about 1:1 to 1:3, and then crystallizing naphthalene from the solution, preferably in 1 to 3 stages, melting the resulting crystalline naphthalene and treating with clay, resuIts in a colour-stable naphthalene.
In a preierred process~'naphthalene is crystallized from a solution in methanol in two stages and subsequently treated with about l to 10%'by weight of clay at a temperature :~23~iZ
in the range of about 82 to 100C. for at least about thirty minutes.
The surprising effect of the present invention consists in the ~act that refinea naphthalene obtained by crystallization from a solution in methanol contains sufficiently low a level of phenolic and unsaturated compounds so that simple clay treatment can remove these impurities below the threshold level necessary to avoid discolouration. Refined naphthalene with a melting point of 79.8C. obtained by melt crystallization, on the other hand, and subsequently also treatea with clay, exhibits too high a phenolic and indene content so that no colour stability results upon exposure to air and light.
The present invention provides a process for the production of colour-stable naphthalene comprising the steps of forming a solu~ion of naphthalene oil and methanol, crystallizing naphthalene from the solution, melting crystall-ine naphthalene and treating the melted crystalline naphthalene with clay to form a colour-stable naphthalene having a minimum melting point of 80C.
In a further embodiment of the invention, the naphthalene is filte~ed after the treatment with clay and distilled to yield naphthalene with a purity of about 99%.
Coal tar naphthalene oil is derived from coal tar in the normal manner by distillation and purification. A
m~thball grade naphthalene should preferably have a purity of about 99~ and a minimum mel-ting point of 80C~
Three examples illustrate comparative tests, Examples 1 and 2 show colour-stable naphthalene made according to the process of the present invention and Example 3.illustrates the effect of melt crystallization in four stages~ The table shows the results of the tests, as can be seen, Examples 1 and 2 produce colour-stable naph-thalene whPreas Example 3~ which is the melt crystallization process, does not.
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~23~
Example 1 Coal tar naphthalene oil, with a ~elting point of 69.5C.,was dissolved at 60C. in methanol and cooled to ambient temperature. The crystals ~ormed in the first crystallization stage by precipitation were~separated by oentrifugation. The naphthalene crystals made in the first stage were further purified by dissolving in pure methanol followed by a second crystallization stage. The ratio of methanol to naphthalene oil used in this example for both crystalli~ation stages was 2:1. The crystals of the second cry~tallization stage were melted~ passed to a process vessel and treated with 5% clay for 1 hour at 85C. After filtration,the naphthalene treated with clay was distilled 15` to yield a colour-stable naphthalene having a melting point of 80.1C. and a purlty of 99.6%.
.
Example 2 A naphthalene oil with a lower naphthalene content was used in this example. By applying similar crystallization conditions refined naphthalene crystals of the second crystallization stage were obta~ned which contained only lOOppm phenolics. By further treatmen-t with clay as out-lined in Example 1~ and subsequent filtration and distill-ation, colour-stable naphthalene having a melting point of 80.05~C. was obtained.~ The purity of the naphthalene was 99.52%.
.
Example 3 Refined naphthalene obtained by crystalli~ation from the melt in four stages was used for comparison. This material was treated with clay as outlined in Example 1.
The final naphthalene product however, was not colour-stablel but discoloured upon exposure to light and air. The melting point was below 80C. and the purity was belaw 99~.
When two or more crystallization stages are .. , utilized, methanol from the second stage crystallization may be-recycled for dissolving the naphthalene oil for the first crystallization stage.
Whereas the separation of crystals may be by centrifuge, other separation methods known to those skilled in the art of coal tar refinin~ such as filtration, may be used.
Various changes may be made to the processes described herein without depar-ting from the scope of the 10: present invention which is l~mitèd only by the following claims.
30.
-- 1 ~
PROCESS FOR THE PRODVC~;CON OF NAPH'rHAI,ENE
The invention relates to a process for the pro-duction of refined naphthalene of mothball colour-stable quality from coal-derived crude naphthalene oil.
Naphthalene is a widely used starting raw material for the organic chemical industry. Thus, large quantities of naphthalene are used for the production of phthalic anhydride, for the manufacture of ~C and ~, naphthol and other organic intermediates ~.S. Stobaugh, Hydroc. Processing, Vol. 45, No. 3, P. 149, 1966). Considerable quantities of very pure naphthalene are used for the manufacture of moth-balls.
One method of obtaining naphthalene is by first distilling coal tar and further purifying the distillate boiling between 205 ana 235Co The resulting coal tar fraction which is generally called naphthalene oil, contains naphthalene, methylnaphthalene, phenolic compounds and heterocyclic constituents such as thionaphthene ~G. Gilbert et al, Ind.
Eng. Chem. Vol. 53, No. 12, p.993, 1961) as well as unsaturated compounds such as indene and its alkylated derivatives.
The naphthalene-content of the naphthalene oil generally varies between about 75 - 90%; the quality of the naphthalene oil is usually characterized by its melting point which ranges from about 65 to 75C~ according to the naphthalene content of the naphthalene oil. In order to produce refined naphthalene with a melting point of about 19.6C. the impurities con-tained in a naphthalene oil have 30 to be removed by chemical and physical processes. The extent of the purification depends on the final application of the naphthalene product. Naphthalene for the manufacture of phthalic anhydride usually has a melting point of 78 - 79C.
whereas naph-thalene of moth~all grade has a minimum melting A
..
,.
~3'~6~
point of 80C and in addition, must not discolour upon exposure to air and light.
Because of the importance of this aromatic compound, the purification and isolation of naphthalene from coal tar fractions have been subjècts of considerable attention.
Traditionally refined naphthalene was produced by washing the naphthalene oil wi-th suIfuric acid followed by aqueous sodium hydroxide. Recently, however, crystalliz-ation processes from the melt have gained importance because they can offer advantages in terms of yield and cause no environmental problems associated with the disposal of acid sludge. A typical process for the production of refined naphthalene from the melt is dèscribed by K. Saxer et al, AIChE meeting, ~ov . ~5 ~9, 1979. Thus naphthalene of a purity of at least 99.7 ~ . could be produced in high yield-using six stages and starting from a naphthalene oil which contained already 90% (melting point 74.1C).
Another process based on the principle of melt crystalliæation is described by I.A. Brodie, Mech. Chem. Eng.
TranS. Inst. of Eng. Austr. 1971, page 37 - 44. For this process too~ a highly concentrated naphthalene oil is recommended for the optimum use of this crystallization technology. Preferably, these crystallization technologies are applied when a highly concentrated starting material is available; otherwise yield and efficiency are adversely affected.
However, a small number of tar refineries are in a position to produce naphthalene oil with a melting point of 73C. or higher~ equivalent to a naphthalene content of 87% or higher. Thus it can be advantageous to resort to different refining methods in order to produce naphthalene of high purity.
A further aspect has to be considered in the production of mothball grade naphthalene. Naphthalene usuable 3.6a~;
for the manufacture of mothballs must retain colour stability upon exposure to air and ligh* for a period of at least two weeks; thus the impurities still contained in refined naphthalene have to be removed below a certain threshold le~el. The mechanism of discolouration is not fully understood; it ls, however, generally assumed that unsaturated compounds such as indenes and phenolic con-stituentS have a discolourating effect.
Many attempts have been made in thè past to produce naphthalene of mothball grade in an economic way. Tradition-ally sublimination processes have been used to produce naphthalene of mothball grade, this methodr however, is extremely costly. Other chemical processes have been dascribed in the literature (H.G. Franck and G. Collin, Steinkohlenteer, Springer, 1968J. These processes, however, turned out to be not generally accep-table because of high cost Ihydrogen treatment) or difficuIt process conditions (partial chlor-ination or reaction with FeC13).
British patent 651,514 describes treating naphth-alene with silica ge~. The-silica gel used in this process had to be considerably modified by washing it free of sulfate anions. No indication as to the indene content of the final naphthalene product is disclosed.
Clay treatment of petroleum derived naphthalene is di5closed by R.B. Stobaugh (Hydrocarbon Processing, Vol.
45, No. 3, page 149f 1966) but this cannot be compared with the refining of coal tar derived naphthalene as petroleum derived naphthalene contains markedly different impurities.
The diEficulty of producing colourless naphthalene from coal tar fractions with inorganic adsorbents is additionally documented in a Russian paper (Zh. I. Repina et al, Koks i Khimya~ No. 9, page 27, 1980). Thus it has been a constant challenge for the manufacturer of mothball grade naphthalenè to develop an economic way for ~3~6~
the pr~ductio~ of mothball g~ade naphthalene~ or in other words, to produce refined naphthalene which contains a sufficiently low level of impurities to render' the refined naphthalene colour-stable.
Methanol has been used as a solvent for washing naphthalene crystals crystallized from naphthalene oil.
British patent no. '686,1'66 discloses such a process. However, it has been found that naphthalene having a melting point above80C. produced by methanol washing of naphthalene crystals in a limited number of stages, discolours upon exposure to light and air. According to the prior art it is not possible to make a colour~stable naphthalene by this method. (H.G. Franck, G. Collin,'Steinkohlenteer~ ~pringer, Page 70, 1968; and G. Gilbert,'Ind. Eng. Chem., Vol. 53, No. 12 r Page 993, 1961).
Likewise the prior art indicates that a refined naphthalene having a melting point above 79.6C. discolours if the materiaI is produced by crystallization from the melt in a limited number of stages or by the traditional refining process wlthou-t using sulfuric acid and caustic soda.
Surprisinglyt 'a novel method has been found for the production of naphthalene of mothball quality which can be performed in a very economic way, additionally, this novel process is very versatile as to the naphthalene con-tent of thè star-ting naphthalene oil fraction.
It has been found that by dissolving naphthalene oil distilled from coal tar, in methanol, preferably at a naphthalene to methanol ratio in the range of about 1:1 to 1:3, and then crystallizing naphthalene from the solution, preferably in 1 to 3 stages, melting the resulting crystalline naphthalene and treating with clay, resuIts in a colour-stable naphthalene.
In a preierred process~'naphthalene is crystallized from a solution in methanol in two stages and subsequently treated with about l to 10%'by weight of clay at a temperature :~23~iZ
in the range of about 82 to 100C. for at least about thirty minutes.
The surprising effect of the present invention consists in the ~act that refinea naphthalene obtained by crystallization from a solution in methanol contains sufficiently low a level of phenolic and unsaturated compounds so that simple clay treatment can remove these impurities below the threshold level necessary to avoid discolouration. Refined naphthalene with a melting point of 79.8C. obtained by melt crystallization, on the other hand, and subsequently also treatea with clay, exhibits too high a phenolic and indene content so that no colour stability results upon exposure to air and light.
The present invention provides a process for the production of colour-stable naphthalene comprising the steps of forming a solu~ion of naphthalene oil and methanol, crystallizing naphthalene from the solution, melting crystall-ine naphthalene and treating the melted crystalline naphthalene with clay to form a colour-stable naphthalene having a minimum melting point of 80C.
In a further embodiment of the invention, the naphthalene is filte~ed after the treatment with clay and distilled to yield naphthalene with a purity of about 99%.
Coal tar naphthalene oil is derived from coal tar in the normal manner by distillation and purification. A
m~thball grade naphthalene should preferably have a purity of about 99~ and a minimum mel-ting point of 80C~
Three examples illustrate comparative tests, Examples 1 and 2 show colour-stable naphthalene made according to the process of the present invention and Example 3.illustrates the effect of melt crystallization in four stages~ The table shows the results of the tests, as can be seen, Examples 1 and 2 produce colour-stable naph-thalene whPreas Example 3~ which is the melt crystallization process, does not.
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~23~
Example 1 Coal tar naphthalene oil, with a ~elting point of 69.5C.,was dissolved at 60C. in methanol and cooled to ambient temperature. The crystals ~ormed in the first crystallization stage by precipitation were~separated by oentrifugation. The naphthalene crystals made in the first stage were further purified by dissolving in pure methanol followed by a second crystallization stage. The ratio of methanol to naphthalene oil used in this example for both crystalli~ation stages was 2:1. The crystals of the second cry~tallization stage were melted~ passed to a process vessel and treated with 5% clay for 1 hour at 85C. After filtration,the naphthalene treated with clay was distilled 15` to yield a colour-stable naphthalene having a melting point of 80.1C. and a purlty of 99.6%.
.
Example 2 A naphthalene oil with a lower naphthalene content was used in this example. By applying similar crystallization conditions refined naphthalene crystals of the second crystallization stage were obta~ned which contained only lOOppm phenolics. By further treatmen-t with clay as out-lined in Example 1~ and subsequent filtration and distill-ation, colour-stable naphthalene having a melting point of 80.05~C. was obtained.~ The purity of the naphthalene was 99.52%.
.
Example 3 Refined naphthalene obtained by crystalli~ation from the melt in four stages was used for comparison. This material was treated with clay as outlined in Example 1.
The final naphthalene product however, was not colour-stablel but discoloured upon exposure to light and air. The melting point was below 80C. and the purity was belaw 99~.
When two or more crystallization stages are .. , utilized, methanol from the second stage crystallization may be-recycled for dissolving the naphthalene oil for the first crystallization stage.
Whereas the separation of crystals may be by centrifuge, other separation methods known to those skilled in the art of coal tar refinin~ such as filtration, may be used.
Various changes may be made to the processes described herein without depar-ting from the scope of the 10: present invention which is l~mitèd only by the following claims.
30.
Claims (12)
1. A process for the production of colour-stable naphthalene from coal tar that comprises crystallizing naphthalene from a solution of crude naphthalene in methanol, melting crystalline naphthalene followed by clay treatment to produce refined naphthalene.
2. A process as claimed in Claim 1 in which the crystallization is carried out in 1 to 3 stages.
3. A process as claimed in Claim 1 in which the ratio of naphthalene to methanol is in the range of about 1:1 to 1:3.
4. A process as claimed in Claim 1 in which the quantity of clay used to treat the refined naphthalene is in the range of about 1 to 10% by weight.
5. A process as claimed in Claim 1 in which the treatment of the refined naphthalene with clay is carried out at a temperature in the range of about 82 to 100°C.
6. A process for the production of colour-stable naphthalene comprising the steps of:
forming a solution of naphthalene oil coal tar fraction and methanol;
crystallizing naphthalene from the solution;
melting crystalline naphthalene and;
treating the melted crystalline naphthalene with clay to form a colour-stable naphthalene having a minimum melting point of 80°C.
forming a solution of naphthalene oil coal tar fraction and methanol;
crystallizing naphthalene from the solution;
melting crystalline naphthalene and;
treating the melted crystalline naphthalene with clay to form a colour-stable naphthalene having a minimum melting point of 80°C.
7. The process according to Claim 6 wherein the ratio of the naphthalene oil tar fraction and methanol in the solution is in the range of about 1:1 to 1:3.
8. The process according to Claim 6 wherein the steps of forming a solution and crystallizing are carried out in 1 to 3 stages.
9. The process according to Claim 8 wherein the melted crystalline naphthalene is treated with clay in the range of about 1 to 10% by weight.
10. The process according to claim 9 wherein the melted crystalline naphthalene is treated with clay at a temperature in the range of about 82 to 100% C. for at least about thirty minutes.
11. The process according to claim 6 including filtering the naphthalene after the treatment with clay and distilling to yield naphthalene with a purity of at least about 99%.
12. The process according to claim 6 wherein the naphthalene oil coal tar fraction is dissolved in methanol above ambient temperature, and allowed to cool to ambient temperature for crystallizing.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000475666A CA1234162A (en) | 1985-03-04 | 1985-03-04 | Process for the production of naphthalene |
| ZA851811A ZA851811B (en) | 1985-03-04 | 1985-03-11 | Process for the production of naphthalene |
| BE2/60648A BE901970A (en) | 1985-03-04 | 1985-03-19 | PROCESS FOR PRODUCING NAPHTHALENE. |
| JP60275854A JPS61200931A (en) | 1985-03-04 | 1985-12-06 | Manufacture of color-stable naphthalene |
| CN86100936.3A CN1003643B (en) | 1985-03-04 | 1986-02-04 | Process for the production of naphthalene |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000475666A CA1234162A (en) | 1985-03-04 | 1985-03-04 | Process for the production of naphthalene |
| BE2/60648A BE901970A (en) | 1985-03-04 | 1985-03-19 | PROCESS FOR PRODUCING NAPHTHALENE. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1234162A true CA1234162A (en) | 1988-03-15 |
Family
ID=25661821
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000475666A Expired CA1234162A (en) | 1985-03-04 | 1985-03-04 | Process for the production of naphthalene |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS61200931A (en) |
| CN (1) | CN1003643B (en) |
| BE (1) | BE901970A (en) |
| CA (1) | CA1234162A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113150811A (en) * | 2020-01-07 | 2021-07-23 | 上海圣升化工科技有限公司 | Coal tar deep processing technology |
-
1985
- 1985-03-04 CA CA000475666A patent/CA1234162A/en not_active Expired
- 1985-03-19 BE BE2/60648A patent/BE901970A/en not_active IP Right Cessation
- 1985-12-06 JP JP60275854A patent/JPS61200931A/en active Pending
-
1986
- 1986-02-04 CN CN86100936.3A patent/CN1003643B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CN1003643B (en) | 1989-03-22 |
| JPS61200931A (en) | 1986-09-05 |
| BE901970A (en) | 1985-07-16 |
| CN86100936A (en) | 1986-09-10 |
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