FIELD

The present disclosure relates to hydrocarbons and petrochemicals. DEFINITIONS The unit "ppmw" represents parts per million weight, which is a subunit of ppm used to express part of weights like milligrams per kilogram (mg/kg).

Oxygenates refer to oxygen containing compounds like ethers, alcohols, acids present in hydrocarbon feed.

The unit "barg", a unit of gauge pressure, is used for expressing pressure in bars above ambient or atmospheric pressure.

BACKGROUND

Olefins are major building blocks for various petrochemicals. Owing to relatively high reactivity of olefins, their demand is always increasing. Different olefin products such as ethylene, propylene, butadiene, butane, butene, isoprene, pyrolysis gasoline, and the like are produced using steam cracker.

Olefins are produced in the stream cracker using naphtha as a feedstock. Naphtha is an intermediate hydrocarbon liquid stream obtained during distillation of crude oil or thermal and/or catalytic cracking of hydrocarbon streams. Naphtha contain large amount of oxygen compounds, commonly called as oxygenates. These oxygenates are undesired contaminants for naphtha cracker units, and its downstream equipment. Naphtha fraction with relatively high concentration of oxygenates, as impurities, is of particular concern to naphtha crackers, and various other catalytic conversion processes, as the oxygen containing compounds increase corrosion, and fouling rates in the downstream equipment. The oxygen containing compounds are also responsible for poisoning the catalyst. The acceptable level of oxygenates in the hydrocarbon feed is 50 ppmw.

Hence, there is a need to provide a process for reducing the oxygenate content of the hydrocarbon feed. OBJECTS

Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:

An object of the present disclosure is to provide a process for reducing the oxygenate content of hydrocarbon feed.

Another object of the present disclosure is to provide a process that is simple and environment friendly for reducing the oxygenate content of hydrocarbon feed.

Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

SUMMARY

The present disclosure provides a process for reducing oxygenate content of hydrocarbon feed. The process comprises the following steps:

(i) passing and heating the hydrocarbon feed over ion exchange resin resident in a reactor, maintained at a temperature in the range of 90 to 140 °C and at a predetermined pressure, at a predetermined liquid hourly space velocity to obtain a heated intermediate fluid;

(ii) cooling the heated intermediate fluid to obtain a cooled intermediate fluid;

(iii) mixing the cooled intermediate fluid with water to obtain a mixture;

(iv) allowing the mixture to settle to obtain an aqueous phase and an organic phase; and

(iv) separating the aqueous phase from the organic phase to obtain hydrocarbon feed with reduced oxygenate content.

In accordance with the present disclosure, the oxygenate in the hydrocarbon feed comprises at least one of methyl tertiary butyl ether (MTBE) and tertiary amyl methyl ether (TAME).

Typically, in accordance with the present disclosure, the oxygenate in the hydrocarbon feed comprises at least one of methanol, ethanol, 1-propanol, 2-butanol, 1-butanol and tertiary amyl alcohol. Typically, in accordance with the present disclosure, the amount of the oxygenate content in the hydrocarbon feed is in the range of 51 to 350 ppmw.

Typically, in accordance with the present disclosure, the amount of the oxygenate content in the hydrocarbon feed with reduced oxygenate content is in the range of 4 to 50 ppmw. Typically, in accordance with the present disclosure, the ion exchange resin is a cation exchange resin.

Typically, in accordance with the present disclosure, the ion exchange resin is a macroporous polymeric exchange resin.

Typically, in accordance with the present disclosure, the ion exchange resin is a macroporous polymeric sulphonic acid exchange resin.

Typically, in accordance with the present disclosure, the process comprises a pre-step of drying the ion exchange resin before using it in step (i).

Typically, in accordance with the present disclosure, the predetermined pressure is in the range of 4 to 10 barg. Typically, in accordance with the present disclosure, the predetermined liquid hourly space velocity is in the range of 0.5 to 15 per hour.

Typically, in accordance with the present disclosure, the hydrocarbon feed is petrochemical naphtha comprising C5 to C8 hydrocarbons.

Typically, in accordance with the present disclosure, the reactor is a fixed bed reactor. Typically, in accordance with the present disclosure, wherein quantity of the water used in step (iii) is in the range of 2.5 to 10 vol of the hydrocarbon feed, wherein the water used in step (iii) is demineralized water.

DETAILED DESCRIPTION

Petrochemical naphtha contain large numbers of oxygen containing compounds or oxygenates, which are of particular concern to naphtha crackers, which makes the feedstock unsuitable for processing. Oxygenates tend to increase corrosion and fouling rates in downstream equipment, while also reacting with the catalyst present in the naphtha cracker and reducing its activity. Oxygenates in hydrocarbon feed mainly include alcohols and ethers. Alcohols being water- soluble can be easily removed from the hydrocarbon feed by washing, however ethers being essentially non-polar molecules are sparingly soluble in water. As a result, the total oxygenates cannot be removed from petrochemical naphtha stream by simply washing with water.

Ethers can be removed from hydrocarbon feed easily if they are converted to alcohols. Ethers can be converted to olefins and alcohols in the presence of an acid. The alcohol molecules thus formed can be easily removed on washing the hydrocarbon feed with water.

The present disclosure envisages a process for reducing oxygenate content of hydrocarbon feed. The process is carried out by converting ethers in the hydrocarbon feed into alcohols using an ion exchange resin and then removing the alcohols in the hydrocarbon feed by washing with water.

The process of the present disclosure comprises the following steps. Initially, the hydrocarbon feed is passed and heated over an ion exchange resin resident in a reactor maintained at a temperature in the range of 90 to 140 °C and a pre-determined pressure at a predetermined liquid hourly space velocity to obtain a heated intermediate fluid. Preferably, the reactor is maintained at a temperature in the range of 100 to 120°C, more preferably at 110 °C. Typically, the reactor is a fixed bed reactor. In an embodiment, the temperature of the reactor bed is measured by use of an axial thermocouple. The heated intermediate fluid is collected after passing over the ion exchange resin. This heated intermediate fluid is cooled to obtain a cooled intermediate fluid. Typically, the heated intermediate fluid is cooled to a temperature in the range of 30 to 40 °C.

Further, the cooled intermediate fluid is mixed with water to obtain a mixture, wherein the quantity of water is in the range of 2.5 to 10 vol of the hydrocarbon feed. Typically, the mixing is carried out by shaking, stirring or by any other means. Typically, the water used is demineralized water.

Furthermore, the mixture is allowed to settle to obtain an aqueous phase and an organic phase. Thereafter the aqueous phase is separated from the organic phase to obtain hydrocarbon feed with reduced oxygenate content. As per an embodiment of the present disclosure, the amount of oxygenate content in the hydrocarbon feed is in the range of 51 ppmw to 350 ppmw. The oxygenate in the hydrocarbon feed comprises alcohols, ethers, acids, and the like. The oxygenate in the hydrocarbon feed comprise at least one of methyl tertiary butyl ether (MTBE) and tertiary amyl methyl ether (TAME). The oxygenate in the hydrocarbon feed comprises at least one of methanol, ethanol, 1-propanol, 2-butanol, 1-butanol and tertiary amyl alcohol.

Typically, the pre-determined pressure is in the range of 4 to 10 barg, preferably from 5 to 7 barg and more preferably 6 barg. Typically, the predetermined liquid hourly space velocity is in the range of 0.5 to 15 per hour. Preferably, the predetermined liquid hourly space velocity is in the range of 0.5 to 10 per hour.

Typically, the ion exchange resin is a cation exchange resin. Typically, the ion exchange resin is a macroporous polymeric resin. In an embodiment, the ion exchange resin used is macroporous polymeric sulphonic acid exchange resin such as Amberlyst. The surface area of ion exchange resin is 50 m 2 e, average pore diameter is 300 A°, total pore volume is 0.35 cc/g, the particle size is in the range of 0.3 to 1.20 mm, and bulk density is 560 kg/m ³ .

In an embodiment of the present disclosure, moisture in the ion exchange resin is at least below 3%. Preferably, the ion exchange resin is dried before use, so as to expel residual moisture, wherein the dried ion exchange resin is stored in a desiccator.

The present disclosure offers an integrated process for reducing the oxygenate content of the hydrocarbon feed. As per an embodiment of the present disclosure, the amount of oxygenate content in the hydrocarbon feed with reduced oxygenate content is in the range of 4 to 50 ppmw. The process of the present disclosure enables reduction of oxygenate content of the hydrocarbon feed by an amount in the range of 70-90 wt%.

The process of the present disclosure can help to achieve desired degree of oxygenate removal, thereby effectively improving the acceptability of naphtha stream as a feedstock. For most of naphtha conversion processes, the desired specification of oxygenate is less than 50 ppmw.

Typically, the hydrocarbon feed is comprised of straight run saturated light naphtha stream having boiling point in the range of 32 to 120 °C. In one embodiment, the hydrocarbon feed is petrochemical naphtha comprising C5 to C8 hydrocarbon which further comprises C5-C8 normal paraffins, iso-paraffins, napthenes and C6-C7 aromatics. Typically, the hydrocarbon feed contains moisture at least below 160 ppmw and metal impurity at least below 100 ppb. The metal impurity in the hydrocarbon feed may be at least one of sodium, potassium, calcium and iron.

The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.

Example 1:

Hydrocarbon feed having an oxygenate content of 150 ppmw, moisture content of 160ppmw and metal content of less than 100 ppb, was passed and heated over an Amberlyst resin present in a fixed bed reactor. The reactor was maintained at 110 °C and 6 barg. The hydrocarbon feed was passed at a liquid hourly space velocity (LHSV) of 7 per hour. The feed from the reactor was cooled to 30 °C and then mixed with 5 vol of water. The resulting mixture was allowed to settle to obtain an aqueous phase and an organic phase. The organic phase was separated from the aqueous phase to obtain hydrocarbon feed with reduced oxygenate content having 20 ppmw of oxygenate content.

Example 2:

Hydrocarbon feed having an oxygenate content of 150 ppmw, moisture content of 160ppmw and metal content of less than 100 ppb, was passed and heated over an Amberlyst resin present in a fixed bed reactor. The reactor is maintained at 110 °C and 6 barg. The effluent from reactor was passed at a liquid hourly space velocity (LHSV) of 7 per hour. The hydrocarbon stream from the reactor was cooled to 30 °C and then mixed with 10 vol of water. The resulting mixture was allowed to settle to obtain an aqueous phase and an organic phase. The organic phase was separated from the aqueous phase to obtain hydrocarbon feed with reduced oxygenate content having less than 20 ppmw of oxygenate content.

TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE

The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a process for reducing the oxygenate content of hydrocarbon feed, wherein the process: enables removal of 70-90% of oxygenate content from the hydrocarbon feed; and is simple and environment friendly.

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. While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation 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 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 unless there is a statement in the specification to the contrary.

While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.