Claims:WE CLAIM,

1. A process for neutralizing spent catalyst, wherein process comprises steps:
Hydrolyzing the spent catalyst with service water;
Mixing of the spent catalyst and allowing the dimerization reaction to the mixture;
Separating the said mixture through Nitrogen Bubbling;
Adjusting the pH of the spent catalyst.

2. The process for neutralizing spent catalyst as claimed in claim 1, wherein the spent catalyst is the catalyst obtained in Butene-1 production.

Dated this 5th day of December, 2020.

Gopi Trivedi (Ms.)
IN/PA 993
Authorized Agent of Applicant
To,
The Controller of Patents,
The Patent Office,
At Mumbai.
, Description:Form 2

The Patents Act,
(39 of 1970)

Complete Specification
(See Section 10; Rule 13)

“A process for neutralization of spent catalyst”

ONGC Petro Additions Limited

ONGC Petro additions Limited (OPaL), Dahej,
Bharuch- 392130, Gujarat, India.

The following specification particularly describes the nature of the invention and the manner in which it is to be performed:

FIELD OF INVENTION:

The present invention relates to a process for neutralization of spent catalyst. More particularly, it relates to process for neutralizing spent Ziegler Natta catalysts generated during the production of Alpha olefin, namely Butene-1 from dimerization reaction of Ethylene.

BACKGROUND OF INVENTION:

Generally, the Butene-1 production is obtained by dimerization of ethylene. Ethylene can be dimerized to Butene-1 using dimerization process in the presence of a catalyst composed of an aluminum based compound and titanium-based catalyst which is known in the art, preferably including those which lead to a high selectivity for dimers (1-butene or 2-butene)
However in the process of production of the Butene-1, the spent catalyst is generated with the impurities of TEAl (Tri Ethyl aluminum), Solution of Titanium complex (N-Butyl Titanate) in tetrahydrofuran), and Amines. The spent catalyst needs to be discarded safely. Also due to large amount of impurities present it cannot be discarded directly nor is it accepted by the local incinerator vendors due to pyrophoric nature of spent catalyst and presence of other impurities.
In the past, spent catalyst has often been generated from a catalyst recovery section and sent to incinerator for safe disposal. In some cases, spent catalyst was neutralized with basic material after being separated from the reaction, but, this particular system requires acidic treatment to neutralize as PH increases. Such catalysts become spent, But, the prior art disposal techniques are not entirely satisfactory from safety and environmental standpoints, as dumping of spent non-neutralized catalyst generates considerable toxic waste, highly pungent smell and pyrophoric spent which creates safety and environmental issues.
In light of the aforementioned discussion, there exists a need for a process that would overcome the above mentioned disadvantages.

PRIOR ART AND ITS DISADVANTAGES:

The US patent application US5728912A relates to an improved industrial process for the manufacture of Butene-1 from ethylene. The object of the present invention is to provide an improved process for manufacture of butene-1 by dimerization of ethylene comprising a very efficient catalyst removal section. The process of the invention in which about 99 wt % of the reactor effluent is vaporised in two stages, first using an ordinary vaporizer and then thin film evaporator, has the advantage of limiting vaporization duty on the thin film evaporator. This limitation decreases the plant cost significantly. Moreover, the vaporization at high temperatures and pressures causes frequent fouling of vaporizer due to polymer properties modification at high temperature in the vaporizer. In the process of the invention, high temperatures are avoided so that fouling of the vaporizer is efficiently limited. In the dimerization process of ethylene, the reactor effluent always contains some heavy components such as C6 (mainly olefinic compounds) and C6+ (mainly octenes) formed by side reaction in the reactor.
Another US patent application US20130158321A1 relates to a process for production of octenes from ethylene by dimerizing ethylene to butenes and by dimerizing butenes to octenes. The process employs the following steps: 1. Dimerization of Ethylene to Butenes and 2. Dimerization of Butenes to Octenes. In a first variation, ethylene dimerization is carried out in the presence of a titanium-based catalyst. A homogeneous catalytic system is used which can selectively produce 1-butene from ethylene under mild conditions. The catalytic system is composed of an alkyl titanate, an ether type organic additive and an aluminium compound with formula AlR3 or AlR2H, in which each of the residues R is a hydrocarbyl radical, preferably alkyl containing 2 to 6 carbon atoms, for example triethylaluminium, tripropylaluminium, triisobutylaluminium, the hydride of diisobutylaluminium or trihexylaluminium. In a second variation, ethylene is dimerized in the presence of a catalytic system composed of a nickel compound and an aluminium compound. The very high purity of the butenes obtained from the ethylene dimerization processes of the invention mean that a prior purification step between the ethylene dimerization step and the butenes dimerization step can be dispensed with.
However, the said prior art documents fail to provide the process for neutralization of spent catalysts. They only provide the process for production of Butene-1 or n-butenes by dimerization of ethylene. Therefore, there is a need to provide the process for neutralization of spent catalysts during manufacturing of butenes.

OBJECTS OF THE INVENTION:

The main object of the present invention is directed to provide a process for neutralization of spent catalysts.
In yet another aspect the present invention provides the process for neutralizing the spent catalyst for the catalyst used in Butene-1 production.
In yet another aspect the invention provides the process that neutralizes the spent catalyst used in Butene-1 production in a single process thereby eliminating the need of separate purification or removal process for neutralizing the spent catalyst. Thus is energy efficient and cost effective.
In yet another object of the invention it provides the process for neutralization of spent catalyst that removes the pyrophoric content efficiently form the spent catalyst.
In another object of the invention, it provides the user friendly process.
In yet another object of the invention it provides the process for neutralization of spent catalyst that facilitates safe disposal of solid as well as liquid wastes
In yet another object of the invention is to provide environment friendly process that obviates the disadvantages of prior art.

SUMMARY OF THE INVENTION:
The present process for neutralizing the spent Ziegler Natta catalyst comprises of following steps: 1. Taking water in the neutralizing storage tank; 2. Isolating tank Level Gauge after receiving of water; 3. Providing Nitrogen from the bottom connection for bubbling; 4. Start tank Jacket cooling water for continuous cooling; 5. Maintaining vessel pressure (25 MMWC) by routing overflow line to water tank; 6. Continuing Nitrogen bubbling from the bottom of the connection; 7. Charging spent catalyst; 8. Monitoring the temperature using Thermo Gun and Temperature Gauge (TG) at vessel, if temperature rises by 50°C, stop adding spent catalyst and wait till temperature comes down to 40°C, then repeat from step-6; 9. Keep mixing for 02 hrs and monitoring the tank pressure using Pressure Gauge (PG) provided at top nozzle of the tank; 10. Checking %LEL (Lower Explosive Limit = 20 %) at overflow line, if %LEL is found continuously of 02-meter distance at overflow line, then stop adding spent catalyst till %LEL is normalized, then repeat from step-6; 11.Nitrogen bubbling till next step of draining. 12. Draining the sludge using filter pit system to separate the sludge and effluent water; 13. Routing of the water after dilution; 14. Adding Sulphuric Acid to reduce its pH.

DETAILED DESCRIPTION OF THE INVENTION:
In the proposed invention the features, nature and advantages of the disclosed subject matter will become apparent from the detailed description set forth below.
The present invention provides a process for neutralization of spent catalyst more particularly neutralizing the spent Ziegler Natta catalyst used in Butene-1 production process in plants. Whereas the present process takes into account the following key features:
1. Removal of oxygen impurities in the spent catalyst.
2. Neutralization of TEAl (Tri Ethyl Aluminum),
3. Removal of Titanium complex (N-Butyl Titanate), tetrahydrofuran and amines impurities from the spent catalyst.
4. Removal of pyrophoric contents from the spent catalyst
Materials and chemicals utilized for the present process:
The storage tank with mixing and cooling facility utilized for neutralization of spent catalyst. The storage tank is equipped with Level, temperature, pressure Gauge (LG, TG, PG), Pressure Relief Valve (PSV), spare nozzles to provide Nitrogen (N2), cooling jacket and a dosing connection with in and out tappings.
A pneumatic diaphragm pump with NRV (Non-Return Valve), Thermo Gun, Temperature Gauge (TG), Pressure Gauge (PG), Check Valve (CV), Spent Catalyst Container.
Chemicals used in the process are: Normal process Water, Sulphuric acid, Nitrogen N2.
The present process for neutralizing the spent catalyst comprises of following steps:
1. Hydrolyzing the spent catalyst with normal service water
2. Mixing of the spent catalyst and allowing exothermic reaction to the mixture.
3. Separating the said mixture through Nitrogen Bubbling and screening.
4. Adjusting the pH of the spent catalyst effluent water.
Step 1:
For hydrolyzing the spent catalyst, Normal process/service water is taken in said neutralizing storage tank. The storage tank is equipped with Level Gauge (LG), Temperature Gauge (TG), Pressure Gauge (PG), jacketed cooling water, spare nozzles for Nitrogen (N2) and a dosing connection with in and out tapping.
Once the required amount of Normal process water is taken in the tank, Level gauge (LG) is isolated from the neutralizing storage tank. Jacket cooling water is started and Nitrogen gas (N2) is added from the bottom of the tank through check valve (CV).During this the tank pressure is maintained in range (25 MMWC).
Step 2:
The next step in the process is mixing of the spent catalyst in the said tank for neutralization process. Spent catalyst from said Spent Catalyst Container are charged in said tank and allowed to react. Ensuring the transfer rate of addition to be of 300-400 Kg for minimum of 30-40 minutes in 2-3m3 of water.
Step 3:
As the further step the nitrogen gas (N2) is added to the mixture obtained in step 2. This facilitates the separation and setting of the precipitation. During this the temperature and pressure is to be monitored through Temperature Gauge (TG), pressure gauge (PG) at vessel. In case where temperature rises by 50° C, adding of the mixture of spent catalyst is to be stopped until the temperature comes down at 40°C. Once the temp is at 40 °C, repeat the above step.
While step 3 is in process, it is required to monitor the %LEL at vent (Lower Explosive Limit). In case if %LEL is found continuously within 02-meter distance at overflow vent line, then addition of the mixture of spent catalyst is to be stopped until %LEL is normalized (zero%). Once %LEL is normalized (Lower Explosive Limit = 20 %) repeat the above step.
The obtained mixture is drained separating the sludge. The waste water separated has pH in the range 9-12.
Step 4:
The pH of the waste water obtained in step 3 is to be adjusted in range of 6-8 if it is to be sent to Effluent treatment plant (ETP). pH of the said sludge is adjusted using sulphuric acid solution. (Ratio 2-3.5ml 6N Sulphuric acid for about 148ml).
The present invention and the manner in which it is performed is described in detail below with working examples and is by the way of illustrations only. Therefore, these examples should not be constructed to limit the scope of the present invention as illustrated below:

EXAMPLE OF LAB TRIAL:
100 ml of demineralized water (DM) is taken in beaker (250 ml) and spent catalyst is added drop-wise cautiously (28ml) with constant stirring by maintaining the temperature within 40 deg C. To the said content, 3.5 ml of 6N sulfuric acid is added drop-wise to neutralize the solution and pH is found lowered to 5~6 (approx.). Greenish yellow precipitate is observed settling at the bottom of resultant solution and the solution is left overnight when aqueous layer is found separated. In order to check suitability for disposal, aqueous layer is analyzed for Chemical Oxygen Demand (COD). The dried yellow precipitate is ignited in a crucible over burner and precipitate is found to burn with a sooty flame.
The spent catalyst neutralized through above process when subjected to Metal Analysis test for both the sludge and precipitate. The result obtained is summarized below and is within the range as permitted under environment norms:
Sample Ash content Ti Al Al2O3
Powder 30.30% 3.37% 2.17% 8.21%
Liquid - 8.1 ppm Not traceable -
Powder 29.49% 0.21% 1.05% 3.99%
Liquid - 9.1 ppm Not traceable -

Table 01: Metal content analysis of neutralized spent catalyst
Having described what is considered the best from presently contemplated for embodying the present invention, various alterations, modifications, and/or alternative applications of the invention for any system will be promptly apparent to those skilled in the art. Therefore it is to be understood that the present invention is not limited to the practical aspects of the actual preferred embodiments hereby described and that any such modifications and variations must be considered as being within the scope and spirit of this invention, as described in the description of invention above.

ADVANTAGES OF THE INVENTION:
• The present invention provides the process for the neutralization of spent catalyst used in Butene-1 production.
• It does not require any additional purification step.
• It efficiently removes the pyrophoric contents in the spent catalyst.
• It is easy for operation.
• It is environment-friendly.
• It provides safe disposal of solid and liquid wastes generated during the production of Butene-1.