FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
A PROCESS FOR PREPARING FURFURYL ALCOHOL
GALAXY LABORATORIES PVT. LTD.
an Indian Company
of Plot No. B-22, MIDC, Aurangabad Industrial Area,
Gut No. 34, Grampanchayat Satara Parisar,
Beed By-pass, Aurangabad,
Maharashtra 431005
Inventors:
1) DESHMUKH SHRIKANT RAMCHANDRA
2) WALIMBENAGESH SAYAJIRAO
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE DISCLOSURE:
The present disclosure relates to a process for preparing furfuryl alcohol.
The present disclosure particularly relates to a process for preparing furfuryl alcohol through catalytic hydrogenation.
BACKGROUND:
Furfuryl alcohol is widely used as a solvent for the production of thermostatic resins, phenolic resins, pigments of low solubility and the like. It is also used as a starting material for the production of adhesives, paints and coatings. Conventional methods for preparing furfuryl alcohol include liquid phase or vapor phase hydrogenation of furfural. In both the cases, hydrogenation of furfural is carried out by adding hydrogen to furfural using a suitable catalyst.
The conventional liquid phase hydrogenation method usually requires purging of hydrogen gas at high pressure, in the range of 100 to 125kg/cm , and at a temperature of around 160°C. It has been observed that these reaction conditions result in undesired by-products such as 2-methyl furane, tetrahydrofurfuryl alcohol and ethers, which reduce the yield and percent purity of furfuryl alcohol.
The conventional vapor phase hydrogenation process for hydrogenation of furfural using copper chromites as catalysts does not involve stringent conditions, however, the capital investment in terms of machinery and poor availability of copper chromites makes this process unfeasible. Some of the prior art disclose methods for preparing furfuryl alcohol by hydrogenation of furfural in the presence of a mixture of a copper-chromite catalyst and oxides of alkali-earth metals, and ceramic material.

However, the copper based catalysts used in the aforementioned hydrogenation methods are highly toxic and cause severe environmental pollution. Further, the selectivity of the copper based catalysts also gets adversely affected with minor deviations in the reaction conditions. Therefore, they are not suitable for commercial use.
Some prior art discloses hydrogenation of furfural into furfuryl alcohol using nickel catalyst, typically, nickel aluminum alloy in place of copper based catalysts. Another prior art discloses a method for production of furfuryl alcohol using liquid phase process in the presence of palladium or rhodium catalysts.
However, the use of these catalysts is not feasible on account of their high reactivity and formation of a large number of unwanted by-products.
Furthermore, the hydrogenation reactors required for these hydrogenation reactions are very expensive and do not commensurate with profitability of furfuryl alcohol production.
Therefore, there exists a need for a simple and selective process which obviates the requirement of copper chromium catalysts, without affecting the yield and quality. Further, there exists a need for a process which can be carried out under more easily attainable temperature and pressure conditions.
OBJECTS:
Some of the objects of the present disclosure, of which at least one embodiment herein satisfies, are as follows:
It is an object of the present disclosure to provide a simple and commercially economic process for preparing high quality furfuryl alcohol from furfural.

It is another object of the present disclosure to provide a process for preparing furfuryl alcohol by liquid phase hydrogenation, without compromising on selectivity.
It is yet another object of the present disclosure to provide a process for preparing furfuryl alcohol under simple conditions involving moderate pressure and moderate temperature, thereby enhancing the safety aspects and reducing costs.
It is yet another object of the present disclosure to provide a process for preparing furfuryl alcohol without the need for expensive equipments.
It is yet another object of the present disclosure to provide a process for preparing furfuryl alcohol which obviates the need of copper chromites or similar catalysts.
SUMMARY:
In accordance with one aspect of the present disclosure there is provided a process for preparing furfuryl alcohol; said process comprising the following steps:
a. mixing furfural and a Raney nickel catalyst at a proportion ranging
between 200:0.1 and 200:5 in a liquid phase hydrogenation reactor
to obtain a first mixture;
b. purging inert gas through the first mixture to remove trapped air,
followed by passing hydrogen gas to replace the inert gas and
maintaining the pressure of said reactor in the range of 0.5kg/cm to
1 kg/cm2
c. heating the first mixture at a temperature ranging between 135°C
and 150°C, in a controlled manner to obtain a second mixture;
d. hydrogenating said second mixture hy purging hydrogen gas at a
pressure ranging between 8 kg/cm2 and 18 kg/cm2 and at a

temperature ranging between 135°C and 150°C to obtain a third mixture comprising at least one compound selected from the group consisting of furfuryl alcohol, tetrahydro furfuryl alcohol and unreacted furfural; and e. distilling the third mixture under vacuum ranging between 5mm Hg and 15 mmHg to fractionate furfuryl alcohol from tetrahydrofurfuryl alcohol and unreacted furfural.
Typically, the proportion of furfural to the Raney nickel catalyst ranges between
200:0.4 and 200:2.
Typically, said Raney nickel catalyst being characterized by:
• a mesh size in the range of 25 to 30 micron;
• pH in the range of 9 to 11; and
• hydrogenation adsorption capacity in the range of 55 to
75(H2)ml/g/min.
Typically, the proportion of furfural to hydrogen gas is in the range of 40:0.9 to
40:14, preferably at a proportion of 40:10 to 40:13.
Typically, the method step (d) is carried out at a temperature ranging between
137oC and 145oC, at a pressure ranging between 10 kg/cm2 to 16 kg/cm2 and
for a time period ranging between 12 hrs. and 32 hrs.
Typically, the purity of furfuryl alcohol is greater than 98 %.
DESCRIPTION:
Various attempts have been made to develop a simple and selective process for hydrogenation of furfural to furfuryl alcohol. However, these processes suffer

from several drawbacks which include high (stringent) pressure and temperature conditions, use of highly reactive hydrogenation catalysts and the like.
Accordingly, the inventors of the present disclosure developed a novel process for catalytic hydrogenation of furfural to furfuryl alcohol. The process allows liquid phase hydrogenation of furfural at a pressure lower than those of the prior art and also utilizes less toxic catalyst, typically a Raney nickel catalyst. The percent purity of furfuryl alcohol obtained in accordance with the present disclosure is greater than 98%.
Therefore, in accordance with the present disclosure, there is provided a process for preparing furfuryl alcohol by liquid phase catalytic hydrogenation of furfural. The process involves the following steps:
In the first step, furfural and a Raney nickel catalyst is mixed at a proportion ranging between 200:0.1 and 200:5 in a liquid phase hydrogenation reactor to obtain a first mixture.
The furfural used in the process of the present disclosure has a purity level of 98.5%, boiling range of 161°C to 163°C, moisture of 0.5%, pH of 5.5 to 6.0 and is a pale yellow liquid.
The hydrogen gas used in the process of the present disclosure has a purity of 99.7%, oxygen content NMT 0.2% at 20 kg /cm2.
The Raney nickel catalyst used in the process of the present disclosure has a mesh size of 25 -30 micron, pH in the range of 9 to 11, and hydrogenation adsorption capacity of 55 to 75(H2) ml/g/min.
In accordance with one of the exemplary embodiments of the present disclosure the proportion of furfural to the Raney nickel catalyst is maintained in the rage of 200: 0.4 and 200: 2.0.

In the second step, an inert gas is purged through the first mixture to remove trapped air, followed by passing hydrogen gas to replace the inert gas. Further, the pressure of the reactor is maintained in the range of 0.5 kg/cm to 1 kg/cm In the third step, the first mixture is heated at a temperature ranging between 135°C and 150°C, in a controlled manner to obtain a second mixture.
In the fourth step, the second mixture is hydrogenated by purging hydrogen gas at a pressure ranging between 8 kg/cm and 18 kg/cm and at a temperature ranging between 135°C and 150°C to obtain a third mixture comprising at least one compound selected from the group consisting of furfuryl alcohol, tetrahydro furfuryl alcohol and unreacted furfural. The time required for conversion of furfural to furfuryl alcohol ranges between 22 hours to 35 hours.
In accordance with one embodiment of the present disclosure the time required for conversion of furfural to furfuryl alcohol ranges between 24 hours to 32 hours.
The ratio of the amounts of furfural and hydrogen gas ranges between 40: 0.9 and 40: 14.0.
In accordance with another exemplary embodiment of the present disclosure the ratio of the amounts of furfural and hydrogen gas ranges between 40: 10.0 and 40: 13.0.
In accordance with yet another embodiment of the present disclosure the second mixture is hydrogenated by purging hydrogen gas at a pressure ranging between 10 kg/cm2 and 16 kg/cm2 and at a temperature ranging between 137°C and 145°C to obtain a third mixture.
The reaction sequence for the catalytic liquid phase hydrogenation of furfural is as follows:


In the fifth step, the third mixture is distilled under vacuum ranging between 5mm Hg and 15mmHg to fractionate furfuryl alcohol from tetrahydrofurfuryl alcohol and unreacted furfural.
By maintaining optimum concentrations of these three components and by employing specific conditions of temperature and pressure, a high selectivity is achieved at relatively low hydrogen pressure, giving over 95% yield.
The present disclosure is further described in the light of the following example which is set forth for illustration purpose only and should not to be construed for limiting the scope of the disclosure.
EXAMPLE:
For experimentation purpose the following pilot plant equipments were used:
1. SS304 autoclave with a capacity of 1200 liters and a working pressure of 35kg/cm with an external jacket & internal cooling coils.
2. SS304 pressure filter with filtration surface of 5 micron pores.
3. SS 304 collection tank with a capacity of 2500 liters, for storing crude furfuryl alcohol.
4. Fractional distillation column dia, of SS 304 with 2000 liters still capacity and with a height of 18 meters, diameter of 600 mm, packed with structured packing (250 Y Type) and equipped with vacuum and receivers for collecting fore run, main run & furfural fraction.

For experimentation purpose the following raw materials were used for production of 900kg of furfuryl alcohol:

S.N. Raw material Specifications Quantity used for the batch
1. furfural Pale yellow liquid, boiling range \6l to 163°C, purity 98.5%, moisture 0.5%, acidity, ph 5.5 to 6.0 1000 kg
2. Raney nickel
catalyst pH 9 to 11, mesh size 25 -30 micron, hydrogenation adsorption capacity 55 to 75(H2)ml/g/min 4kg
3. Hydrogen gas Purity 99.7%, oxygen content NMT 0.2% at 20 kg/cm2 32M3atNTP
Example 1: Step 1:
An autoclave of 1100 liters capacity was charged with specific quantities of furfural and Raney nickel catalyst. The autoclave was closed and flushed with nitrogen to remove any trapped air in the empty space of the autoclave. The autoclave was then flushed with hydrogen to remove nitrogen from the empty place. The hydrogen gas pressure in the autoclave was kept at 0.5 kg /cm2 and the reaction mass was slowly heated at 139°C to 140°C. As the pressure in the autoclave started rising, a very slow purging of hydrogen gas was carried on. The hydrogen gas was maintained at a pressure of 15 to 15.5kg/cm and at a temperature of 139°C to 140°C. Intermittent heating or cooling was applied to maintain these conditions. After 15 hours of reaction, samples were drawn for GC analysis and checked for conversion. At the end of 26 to 27 hours furfuryl alcohol conversion reached 95% to 96% with 4.5% to 3.5% level of un-reacted furfural & with an impurity level of 0.4% to 0.6%. The reaction was stopped at

this stage by applying cooling, hydrogen was released, and the autoclave was flushed with nitrogen. The batch was filtered to get crude furfuryl alcohol.
Step 2:
Crude furfuryl alcohol obtained in the step 1 was taken in a distillation still and distilled under vacuum (5mm of Hg) to recover furfuryl alcohol (99.5%) and furfural (98.5%).
The GC analysis report is shown in Table No. 1 below: Table No. 1

S.N. Composition of Reaction Mixture GC Analysis Report
1. Furfuryl alcohol 95.2 to 96.1%
2. Furfural 4.4 to 3.6%
3. Impurity (Tetrahydro Furfuryl alcohol ) 0.4 to 0.3 5
The GC analysis report to check for conversion is shown in Table No. 2 below: Table No. 2

S.N. Reaction time Conversion rate Un-reacted furfural Impurity level
1. 22-24 hours 85% - 93% 15%-14% 0.25% -0.4%
2. 24-26 hours 93% - 95% 7% - 5% 0.3% - 0.5%
3. 26-27 hours 95% - 96% 4.5%-3.5% 0.4% - 0.6%
4. 27-30 hours 99.5% 0.3% - 0.5% 7.8%-10.35%
The results of the furfuryl alcohol samples analyzed are shown in Table No. 3 below:

Table No. 3

S.N. Test Standard Specifications Results
1. Appearance Clear colorless to yellow light Clear colorless to light yellow
2. Moisture by KF NMT0.3% 0.2%
3. Boiling range 170tol71°C 170to171°C
4. Specific gravity at 20°C 1.12 to 1.13 g/ml 1.126 g/ml
5. Assay by GC NLT 98.00% 99.5%
6. Furfural NMT 0.3% 0.05%
TECHNICAL ADVANCEMENT AND ECONOMIC SIGNIFICANCE
The development of this invention leads to the following advantages:
- the process employed is very simple and requires less capital expenditure;
- the process does not involve stringent reaction conditions of high pressure and high temperature;
- the process uses more easily available Raney nickel catalyst which eliminates dependability on copper based catalysts;
- The manufacturing process is highly cost effective because it is a batch process and also because Raney nickel catalyst is easily accessible and reusable;
- No by-products are formed in the process due to a very high level of selectivity (yields of over 95%); and
- the process eliminates the risk of fire hazards since no organic solvents are used at any stage; the explosive nature of hydrogen gas, particularly in the presence of organic solvents, makes it difficult to use on a commercial scale;

While certain embodiments of the inventions have been described, these embodiments have been presented only by way of example, and are not intended to limit the scope of the invention. Variations or modifications to the processes of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.
The numerical values given for various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention and the claims unless there is a statement in the specification to the contrary.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results.

We claim,
1. A process for preparing furfuryl alcohol; said process comprising the
following steps:
a. mixing furfural and a Raney nickel catalyst at a proportion ranging
between 200:0.1 and 200:5 in a liquid phase hydrogenation reactor
to obtain a first mixture;
b. purging inert gas through the first mixture to remove trapped air,
followed by passing hydrogen gas to replace the inert gas and
maintaining the pressure of said reactor in the range of 0.5kg/cm2
to1 kg/cm
c. heating the first mixture at a temperature ranging between 135°C
and 150°C, in a controlled manner to obtain a second mixture;
d. hydrogenating said second mixture by purging hydrogen gas at a
pressure ranging between 8 kg/cm and 18 kg/cm and at a
temperature ranging between 135°C and 150°C to obtain a third
mixture comprising at least one compound selected from the group
consisting of furfuryl alcohol, tetrahydro furfuryl alcohol and
unreacted furfural; and
e. distilling the third mixture under vacuum ranging between 5mm
Hg and 15 mmHg to fractionate furfuryl alcohol from
tetrahydrofurfuryl alcohol and unreacted furfural.
2. The process as claimed in claim 1, wherein the proportion of furfural to the Raney nickel catalyst ranges between 200:0.4 and 200:2.
3. The process as claimed in claim 1, wherein said Raney nickel catalyst
being characterized by:
• a mesh size in the range of 25 to 30 micron;
• pH in the range of 9 to 11; and

• hydrogenation adsorption capacity in the range of 55 to
75(H2)ml/g/min.
4. The process as claimed in claim 1, wherein the proportion of furfural to
hydrogen gas is in the range of 40:0.9 to 40:14, preferably at a proportion of 40:10 to 40:13.
5. The process as claimed in claim 1, wherein the method step (d) is carried
out at a temperature ranging between 137°C and 145°C, at a pressure ranging between 10 kg/cm to 16 kg/cm and for a time period ranging between 12 hrs. and 32 hrs.
6. The process as claimed in claim 1, wherein the purity of furfuryl alcohol
is greater than 98 %.