Description:FIELD OF THE INVENTION:

The present invention relates to the field of biodiesel and production thereof by using a fixed bed heterogeneous catalyst. Specifically, the present invention relates to fixed bed heterogeneous catalyst and process for preparation thereof.

BACKGROUND OF THE INVENTION:

Energy demand of the world is increasing every day and thus demand for fuels is also increasing. Further, to mitigate climate change and to cut down dependency on non-renewable fuel resources, governments around the world are focusing on renewable fuel resources and biodiesel is one of them.

Biodiesel is a substitute to diesel fuel and biodiesel is derived from the triglycerides of vegetable oils or animal fats. Biodiesel can be produced from various vegetable oils such as palm oil, sunflower, soybean, rapeseed and castor oil using different types of catalysts. To produce biodiesel different types of catalysts are required and some of them are discussed hereinbelow.

WO2016057913A1 discloses a transesterification catalyst that is heterogeneous and a method for preparing said transesterification catalyst are provided. The catalyst can be used in a variety of transesterification reactor configurations including CSTR (continuous stirred tank reactors), ebullated (or ebullating) beds or any other fluidized bed reactors, and PFR (plug flow, fixed bed reactors). The catalyst can be used for manufacturing commercial grade biodiesel, biolubricants and glycerin.

MY176268A discloses a method of production of biodiesel from waste cooking oil by transesterification in methanol. Accordingly, the method includes: a) preparing of alkaline modified zirconia catalyst by mixing zirconia with alkaline nitrate solution followed by drying, calcination and cooling; b) performing transesterification with heterogeneous alkaline modified zirconia catalyst; wherein the alkaline modified zirconia catalyst is selected from group comprising magnesium zirconia (Mg/ZrO2), calcium zirconia (Ca/ZrO2), and strontium zirconia (Sr/ZrO2), heterogeneous catalysis of transesterification of waste cooking oils to biodiesel.

MY175808A discloses a catalyst with a mixed zinc and aluminium oxide base having a spinel structure surstoichiometric in zinc, in which part of the Zn atoms are in the octahedral position, a process for preparation of the same and use of the same in a process for preparation of a compound of linear monocarboxylic acid alcohol esters with 6 - 26 carbon atoms from a vegetable or animal oil, neutral or acid, virgin or recycled, with monoalcohols of 1 - 18 carbon atoms allowing an ester that can be used as a motor fuel or a heating fuel and a pure glycerine to be obtained directly in one or more steps.

US 8,12,4801 discloses processes for preparation of fatty acid alkyl esters. The processes include contacting fatty acid glycerides with alcohols in the presence of a catalyst separating the reaction products from the catalyst and separating the fatty acid alkyl esters from the reaction products. The catalyst includes a metal from Group VIB of the Periodic Table and an element from Group VA of the Periodic Table.

Heterogeneous catalysts have attracted great attention in recent times for use in biodiesel production. The need for development of heterogeneous catalysts has risen due to the fact that homogeneous catalysts used for biodiesel production pose some limitations. Further, homogeneous catalysts have limitations for feeds having TAN, because of high Free fatty acid content. These drawbacks of using homogeneous catalysts include washing of products with water to remove catalyst from the products which results in wastewater generation and loss of biodiesel as a result of washing. Further, the use of intensive biodiesel separation protocol, the corrosive nature of the homogeneous catalysts and impossibility of homogeneous catalyst reuse also limit the use of homogeneous catalysts. However, heterogeneous catalysts have the advantages of easy separation from the product, reusability and eco-friendly.

Accordingly, there is a requirement for heterogeneous catalyst and process for preparing the same for biodiesel production.

OBJECTIVES OF THE PRESENT INVENTION:
It is the primary objective of the present invention to provide a fixed bed heterogeneous catalyst and process for preparation thereof.

It is further objective of the present invention is to provide a process for producing biodiesel from an edible oil feedstock by using the fixed bed heterogeneous catalyst.

It is further objective of the present invention is to provide a process for producing biodiesel from an edible oil feedstock by using the fixed bed heterogeneous catalyst, wherein the catalyst can produce biodiesel from edible oil feedstock containing TAN as high as 90.

It is further objective of the present invention is to provide a process for producing biodiesel from an edible oil feedstock with higher biodiesel selectivity.

SUMMARY OF THE INVENTION

The present invention relates to a process for preparing a fixed bed heterogeneous catalyst, wherein the process comprises steps of dissolving ammonium heptamolybdate salt and an acid in water to prepare a first solution. Followed by adding a metal nitrate salt in the first solution with continued stirring for 30 minutes to prepare a second solution. Then mixing the first solution and the second solution to prepare a third solution and adding a chelating agent in the third solution Thereafter, spraying the third solution onto the alumina extrudates to get the sprayed alumina extrudes, and drying the sprayed alumina extrudes at 120 °C for 4 hours. Thereafter, calcinating the dried extrudes at 500 °C for 4 hours to get the fixed bed heterogeneous catalyst.

The acid is selected from phosphino carboxylic acid, nitrilo triacetic acid, and a combination thereof. The metal nitrate salt is selected from a Calcium nitrate salt, a Zinc nitrate salt, and a combination thereof. The fixed bed heterogeneous catalyst produces biodiesel with feeds containing Total Acid Number (TAN) up to 90. The prepared fixed bed heterogeneous catalyst has biodiesel selectivity of 90.6% to 99.9%.

The present invention also relates to a process for producing biodiesel from an edible oil feedstock, wherein the process comprises steps of introducing the edible oil feedstock, Oxygen, fixed bed heterogeneous catalyst, and a chelating agent into a fixed bed-based reactor, wherein, the fixed bed-based reactor is operated at a temperature of 190°C - 210 °C, a pressure of 2-3 bar, and a Weight Hourly Space Velocity (WHSV) of 0.5-1.0.

The edible oil feedstock is selected from a Palm oil feedstock, used cooking oil feedstock and a combination thereof. The chelating agent is selected from citric acid (CA), Glutamic acid, Nitriloacetic acid, Glutaric acid, Succinic acid, and a combination thereof.

DESCRIPTION OF THE INVENTION:

According to the main embodiment, the present invention discloses a process for preparing fixed bed heterogeneous catalyst for biodiesel production.

Specifically, the present invention provides a process for preparing a fixed bed heterogeneous catalyst, wherein the process comprises steps of dissolving ammonium heptamolybdate salt and an acid in water to prepare a first solution. The acid is selected from phosphino carboxylic acid, nitrilo triacetic acid, and a combination thereof.

Followed by adding a metal nitrate salt in the first solution with continued stirring for 30 minutes to prepare a second solution. The metal nitrate salt is selected from a Calcium nitrate salt, a Zinc nitrate salt, and a combination thereof. Thereafter mixing the first solution and the second solution to prepare a third solution and adding a chelating agent in the third solution.

Thereafter, spraying the third solution onto the alumina extrudates to get the sprayed alumina extrudes, and drying the sprayed alumina extrudes at 120 °C for 4 hours. Thereafter, calcinating the dried extrudes at 500 °C for 4 hours to get the fixed bed heterogeneous catalyst.

The catalyst as disclosed herein has a surface area of 150-200 m2/g, and pore volume of 0.3- 0.5 gm/cc.

The fixed bed heterogeneous catalyst produces biodiesel with feeds containing Total Acid Number (TAN) up to 90. The prepared fixed bed heterogeneous catalyst has biodiesel selectivity of 90.6% to 99.9%.

Examples: Preparation of the fixed bed heterogeneous catalyst
Catalyst A: Required amount of Ammonium heptamolybdate salt and phosphino carboxylic acid were dissolved in water with vigorous stirring to prepare a first solution also referred as MoP solution. Then, the required amount of Calcium nitrate salt was added to MoP solution and continued stirring for 30 minutes to prepare a second solution. This second solution was sprayed onto the alumina extrudates having surface area of 180-300 m2/g and pore volume of 0.4-0.1. The resulting extrudes were dried at 120 °C for 4 hours. Finally, the dried extrudes were calcined at 500 °C for 4 hours.

Catalyst B: Required amount of Ammonium heptamolybdate salt and phosphino carboxylic acid were dissolved in water with vigorous stirring to prepare a first solution also referred as MoP solution. Then, the required amount of Calcium nitrate salt and Zinc nitrate were added to MoP solution and continued stirring for 30 minutes to prepare a second solution. This solution was sprayed onto the alumina extrudates having surface area of 180-300 m2/g and pore volume of 0.4-0.1. The resulting extrudes were dried at 120 °C for 4 hours. Finally, the dried extrudes were calcined at 500 °C for 4 hours.

Catalyst C: Required amount of Ammonium heptamolybdate salt, phosphino carboxylic acid and nitrilo triacetic acid were dissolved in water with vigorous stirring to prepare a first solution also referred as MoP solution. Then, the required amount of Calcium nitrate salt and Zinc nitrate were added to MoP solution and continued stirring for 30 minutes to prepare a second solution. Thereafter, mixing the first solution and the second solution to prepare a third solution and adding a chelating agent in the third solution. This third solution was sprayed onto the alumina extrudates having surface area of 180-300 m2/g and pore volume of 0.4-0.1. The resulting extrudes were dried at 120 °C for 4 hours. Finally, the dried extrudes were calcined at 500 °C for 4 hours.

Chelating agents: Citric acid (CA) or CA and Glutamic acid (Amino acid) or CA and Nitriloacetic acid or CA and Glutaric acid or CA and Succinic acid.

Examples: Process for producing biodiesel from an edible oil feedstock
The present invention also relates to a process for producing biodiesel from an edible oil feedstock, wherein the process comprises steps of introducing the edible oil feedstock, Oxygen, and a fixed bed heterogeneous catalyst into a fixed bed-based reactor, wherein, the fixed bed-based reactor is operated at a temperature of 190°C - 210 °C, a pressure of 2-3 bar, and a Weight Hourly Space Velocity (WHSV) of 0.5-1.0.

Catalyst details are listed below in table 1.

Table 1
Catalyst MoO3 CaO P2O5 ZnO Al2O3 Nitrilo acetic acid as chelating agent
Catalyst A 15 2.5 2.5 0 80 nil
Catalyst B 15 2.5 0.5 1.5 80 nil
Catalyst C 15 2.5 0.5 1.5 80 0.72 wt%

In the first example the feedstock is palm oil with Oxygen of 12.5% and reaction conditions and activity data are listed below in table 2. The fixed bed-based reactor is operated at 200 °C, 2-3 bar Pressure, 0.5-1.0 WHSV.
Table 2
Catalyst Conversion of Palm oil FAME or biodiesel selectivity
Catalyst A 99.0 90.6
Catalyst B 100 92.9
Catalyst C 100 98.9

In the first example the feedstock is used cooking oil and reaction conditions, and activity data are listed below in table 3. The fixed bed-based reactor is operated at 200 °C, 2-3 bar Pressure, 0.5-1.0 WHSV.
Table 3
Catalyst Conversion of used cooking oil FAME or biodiesel selectivity
Catalyst A 100 93.4
Catalyst B 100 94.6
Catalyst C 100 99.9

In the present fixed bed heterogeneous catalyst, the phosphorus source is phosphino carboxylic acid instead of H3PO4 and this improves the phosphorous dispersion in the catalyst.

Further, the combination of CaO, ZnO, MoO3, P2O5 on Al2O3 with nitrilo acetic acid as chelating agent provides better yields of bio diesel and also during process for producing biodiesel the temp of operation can be lowered. The chelating agent improves the dispersion of Molybdenum in the catalyst, and thus improves the activity of the catalyst. Further, feed flow (WHSV) can be enhanced and the catalyst can produce biodiesel with feeds containing TAN as high as 90.
, Claims:1. A process for preparing a fixed bed heterogeneous catalyst for biodiesel production, wherein the process comprises steps of:
dissolving ammonium heptamolybdate salt and an acid in water to prepare a first solution;
adding a metal nitrate salt in the first solution with continued stirring for 30 minutes to prepare a second solution;
mixing the first solution and the second solution to prepare a third solution and adding a chelating agent in the third solution; spraying the third solution onto the alumina extrudates to get the sprayed alumina extrudes;
drying the sprayed alumina extrudes at 120 °C for 4 hours; and
calcinating the dried extrudes at 500 °C for 4 hours to get the fixed bed heterogeneous catalyst.

2. The process as claimed in claim 1, wherein, the acid is selected from phosphino carboxylic acid, nitrilo triacetic acid, and a combination thereof.

3. The process as claimed in claim 1, wherein, the metal nitrate salt is selected from a Calcium nitrate salt, a Zinc nitrate salt, and a combination thereof.

4. The process as claimed in claim 1, wherein, the chelating agent is selected from citric acid (CA), Glutamic acid, Nitriloacetic acid, Glutaric acid, Succinic acid, and a combination thereof.

5. The process as claimed in claim 1, wherein, the chelating agent is .05-1%.

6. The process as claimed in claim 1, wherein, the fixed bed heterogeneous catalyst produces biodiesel with feeds containing Total Acid Number (TAN) up to 90.

7. The process as claimed in claim 1, wherein, the fixed bed heterogeneous catalyst has biodiesel selectivity of 90.6% to 99.9%.

8. A process for producing biodiesel from an edible oil feedstock, wherein the process comprises steps of:
introducing the edible oil feedstock, Oxygen, and fixed bed heterogeneous catalyst into a fixed bed-based reactor, wherein, the fixed bed-based reactor is operated at a temperature of 190°C - 210 °C, a pressure of 2-3 bar, and a Weight Hourly Space Velocity (WHSV) of 0.5-1.0.

9. The process as claimed in claim 8, wherein, the edible oil feedstock is selected from a Palm oil feedstock, used cooking oil feedstock and a combination thereof.