2711 11 00: Sıvılaştırılmış doğal gaz (LNG): Petrol gazları ve diğer gazlı hidrokarbonlar: doğal gaz

General

Unless otherwise indicated, the term ‘ASTM method’ means the methods laid down by the American Society for Testing and Materials.

Note 2

1. The content of aromatic constituents is to be determined by the following methods:

• products with a distillation end point not exceeding 315 °C: EN 15553 method;

• products with a distillation end point exceeding 315 °C: see Annex A to the explanatory notes to this chapter.

2. The expression ‘similar oils” includes, among others, the following mixtures of hydrocarbons:

• synthetic paraffinic diesel fuels, in particular ‘Hydrotreated Vegetable Oils’ (HVO) and ‘Gas to Liquid Fuels’,

• products from renewable sources resulting from the following processes: ‘Biomass to Liquid Fuels’ or ‘Biogas to Liquid Fuels’,

• products from the co-processing of renewable feedstock at refineries with petroleum feedstock.

The following definitions as regards the production of ‘similar oils’ apply:

• ‘Hydrotreating’ means the thermochemical conversion of triglycerides with hydrogen to produce alkanes; it refers to fuel processing. Sources for triglycerides are, in general, fats and oils, suitable waste, residue fat fractions and fat originating from algae.

• ‘Gas to Liquid Fuels’, ‘Biomass to Liquid Fuels’ and ‘Biogas to Liquid Fuels’ mean the conversion of gas into liquid fuels by the Fischer-Tropsch process or equivalent processes. In the case of ‘Biomass to Liquid Fuels’ there is a prior step, converting the biomass into gas.

Additional note 5

1. It is to be noted that, except as provided in additional note 5(n), the exemption applies to the whole of the products used in the specific process.

Accordingly, where a petroleum product is subjected, for example, to alkylation or polymerisation, that part which is not effectively transformed (alkylated or polymerised) also benefits from the exemption.

2. In cases where preliminary treatment is necessary before a ‘specific process’ (see final paragraph of additional note 5), two conditions must be met in order to obtain the benefit of exemption:

(a) the imported product must be effectively subjected to a ‘specific process’, for example, cracking;

(b) the preliminary treatment must be necessary to the ‘specific process’.

The following in particular are regarded as necessary preparatory treatments for products intended for undergoing a ‘specific process’:

(a) degassing;

(b) dehydration;

(c) removal of certain light or heavy products which might interfere with processing;

(d) removal or conversion of mercaptans (softening or sweetening), of other sulphur compounds or of other compounds which might prejudice processing;

(e) neutralisation;

(f) decantation;

(g) desalination.

Any products which may be obtained in the course of a preparatory treatment but which do not undergo a specific process are liable to the customs duties applicable to products ‘for other purposes’, according to the kind and value of the imported goods and on the basis of the net weight of the products so obtained.

Additional note 5(a)

Vacuum distillation means distillation under a pressure not exceeding 400 mbar, measured at the head of the column.

Additional note 5(b)

Redistillation by a very thorough fractionation process means distillation (other than topping) by a continuous or batch process employed in industrial installations using distillates of subheadings 2710 12 11 to 2710 19 48, 2711 11 00, 2711 12 91 to 2711 19 00, 2711 21 00 and 2711 29 00 (other than propane of a purity of 99 % or more) to obtain:

1. isolated high-purity hydrocarbons (90 % or more in the case of olefins, and 95 % or more in the case of other hydrocarbons), mixtures of isomers having the same organic composition being regarded as isolated hydrocarbons.

Only those processes by means of which at least three different products are obtained are admissible, but this restriction does not apply in any instance where the process consists in the separation of isomers. In so far as this concerns xylenes, ethylbenzene is included with xylene isomers;

2. products of subheadings 2707 10 00 to 2707 30 00, 2707 50 00 and 2710 12 11 to 2710 19 48:

(a) with no overlapping of the final boiling point of one fraction and the initial boiling point of the succeeding fraction and a difference of not more than 60 °C between the temperatures at which 5 and 90 % by volume (including losses) distil by the EN ISO 3405 method (equivalent to the ASTM D 86 method);

(b) with an overlapping of the final boiling point of one fraction and the initial boiling point of the succeeding fraction and a difference of not more than 30 °C between the temperatures at which 5 and 90 % by volume (including losses) distil by the EN ISO 3405 method (equivalent to the ASTM D 86 method).

Additional note 5(c)

Cracking is an industrial process for modifying the chemical structure of petroleum products by breaking down the molecules by heating, with or without pressure and with or without the assistance of a catalyst, thus producing, in particular, mixtures of lighter hydrocarbons which may be liquid or gaseous at normal temperatures and pressures.

The chief cracking processes are:

1. thermal cracking;

2. catalytic cracking;

3. steam cracking to obtain gaseous hydrocarbons;

4. hydrocracking (cracking plus hydrogenation);

5. dehydrogenation;

6. dealkylation;

7. coking;

8. visbreaking.

Additional note 5(d)

Reforming is the thermal or catalytic processing of light or medium oils to increase their content of aromatics. Catalytic reforming is used, for example, to convert straight-distillation light oils into light oils with a higher octane number (with a higher content of aromatic hydrocarbons) or into a mixture of hydrocarbons containing benzene, toluene, xylenes, ethylbenzene, etc.

The principal catalytic reforming processes are those employing platinum as the catalyst.

Additional note 5(e)

Extraction by means of selective solvents is the process of separating groups of products with different molecular structures by means of substances having a preferential solvent effect (for example, furfural, phenol, dichlorethyl ether, sulphuric anhydride, nitrobenzene, urea and certain of its derivatives, acetone, propane, ethyl methyl ketone, isobutyl methyl ketone, glycol, N-methyl morpholine).

Additional note 5(g)

Polymerisation is the industrial process, whether or not involving heating or the use of a catalyst, by means of which unsaturated hydrocarbons are made to form their polymers or copolymers.

Additional note 5(h)

Alkylation means any thermal or catalytic reaction in which unsaturated hydrocarbons are united with any other hydrocarbons, in particular, isoparaffins and aromatics.

Additional note 5(ij)

Isomerisation is the reforming of the structure of the constituents of petroleum products without altering their gross composition.

Additional note 5(l)

The following are examples of dewaxing for the purposes of this additional note:

1. dewaxing by cooling (with or without solvents);

2. microbiological treatment;

3. dewaxing by means of urea;

4. molecular sieve treatment.

Additional note 5(n)

Atmospheric distillation means distillation carried out at a pressure of about 1 013 mbar, measured at the head of the column.

Additional note 6

1. ‘Chemical transformation’ means any operation for the molecular modification of one or more constituents of a petroleum product undergoing processing.

The mere mixing of a petroleum product with another product, whether or not also of petroleum, is not regarded as a ‘chemical transformation’. The incorporation of white spirit into paint, for example, or of a base oil into printing ink, is not to be regarded as falling within the definition of ‘chemical transformation’. This is also the case with all uses of petroleum products as solvents or fuels.

2. Examples of ‘chemical transformations’:

(a) treatment with halogens or halogen compounds:

(i) reaction with propylene present in a gaseous petroleum fraction, in order to obtain organic derivatives (for example, to obtain propylene oxide);

(ii) treatment of petroleum fractions (motor spirit, kerosene, gas oil), paraffins, petroleum waxes or paraffinic residues with chlorine or chlorine compounds, in order to obtain chloroparaffins;

(b) treatment with bases (for example, sodium, potassium, ammonium hydroxides), in order to obtain naphthenic acids;

(c) treatment with sulphuric acid or its anhydride:

(i) to obtain sulphonates;

(ii) to extract or obtain isobutylene;

(iii) for the sulphonation of gas oils and lubricating oils.

Oil added after sulphonation is not eligible for exemption;

(d) sulphochlorination;

(e) hydration, particularly for obtaining alcohols by modification of unsaturated hydrocarbons present in gaseous petroleum fractions;

(f) treatment with maleic anhydride, in particular, treatment of butadiene mixed with a gaseous petroleum fraction containing four carbon atoms, in order to obtain tetrahydrophthalic acid;

(g) treatment with phenol, for example, reaction of petroleum olefins with phenols in the presence of a catalyst, in order to obtain alkylphenols;

(h) oxidation:

(i) oxidation of heavy oils to obtain bitumens of subheading 2713 20 00;

(ii) oxidation of any petroleum product, in order to obtain more complex chemical products such as acids, aldehydes, ketones, alcohols; for example, oxidation of light fractions under heat and pressure, to obtain acetic, formic, propionic and succinic acids;

(ij) dehydrogenation, for example, of:

(i) naphthenic hydrocarbons, to obtain aromatic hydrocarbons (for example, benzole);

(ii) paraffinic hydrocarbons, to obtain liquid olefins as used, for example, in the manufacture of biodegradable alkylbenzenes;

(k) oxo synthesis;

(l) irreversible incorporation of heavy oils into high polymers (for example, into latex of natural or synthetic rubber, butyl rubber, polystyrene);

(m) manufacture of products of heading 2803;

(n) nitration, to obtain nitrated derivatives;

(o) biological treatment of certain petroleum fractions containing n-paraffins, to obtain proteins or other complex organic products.

1. Scope

This test method covers the determination of the content of aromatic and non-aromatic constituents in mineral oils.

2. Definition

2.1. Aromatic constituents: the portion of the sample dissolved in the solvent and adsorbed on silica gel. The aromatic constituents may contain: aromatic hydrocarbons, condensed naphthenic-aromatics, aromatic olefins, asphaltenes, aromatic compounds containing sulphur, nitrogen, oxygen and polar aromatics.

2.2. Non-aromatic constituents: the portion of the sample which is not adsorbed on silica gel and which is eluted by the solvent (such as non-aromatic hydrocarbons).

3. Principle of the method

The sample, dissolved in n-pentane, is allowed to percolate through a special chromatography column packed with silica gel. The nonaromatic constituents, eluted with solvent, are collected subsequently and assayed by weighing after the solvent has evaporated.

Samples not dissolving in n-pentane should be dissolved in cyclohexane.

4. Apparatus and reagents

Chromatography column: this is a glass tube with the dimensions and shape shown in the accompanying sketch. The top aperture must be capable of being sealed by a glass joint having its ground flat face pressed against the top of the column by two rubber-covered metal clamps. The seal must be completely leak tight against an applied pressure of nitrogen or air.

Silica gel: fineness of 200 mesh or more. It must be activated for seven hours in an oven kept at 170 °C before use and placed in a desiccator to cool. After activation, the silica gel must be used within a few days.

Solvent I n-pentane: minimum 95 % pure, aromatic-free.

Solvent II cyclohexane: minimum 98 % pure, aromatic-free.

5. Procedure 1 (chromatography column 1)

Preparation of the sample solution: dissolve approximately 3,6 g (exactly weighed) of the sample in 10 ml of n-pentane (I). If the sample is insoluble in n-pentane, dissolve it in cyclohexane and the determination is performed using cyclohexane (II) instead of n-pentane (I).

Pack the chromatography column (chromatography column 1) with the previously activated silica gel, up to about 10 cm from the upper glass bulb, by carefully tamping the contents of the column with a vibrator so as not to leave any channels. Then insert a plug of glass wool in the top of the silica gel column.

Pre-moisten the silica gel with 180 ml of solvent (I) or (II), and apply a pressure of air or nitrogen from above until the upper surface of the liquid reaches the top of the silica gel.

Carefully release the pressure inside the column and pour over it approximately 3,6 g (exactly weighed expression with 2 decimals) of sample dissolved in 10 ml of solvent (I) or (II), then rinse out the beaker with another 10 ml of solvent (I) or (II), and pour this also over the column.

Apply the pressure progressively while allowing the liquid to flow in drops from the bottom capillary tube of the column at the approximate rate of 1 ml/min and collect this liquid in a 500 ml flask.

When the level of the liquid containing the substance to be separated falls to the surface of the silica gel, carefully remove the pressure once more and add 230 ml of solvent (I) or (II), re-apply the pressure immediately and bring down the level of the liquid to the surface of the silica gel while collecting the eluate in the same flask as before.

Before the level of the liquid containing the substance to be separated falls to the surface of the silica gel, check the eluate using FT-IR for the presence of aromatics. If the eluate contains only aliphatic hydrocarbons, add again 50 ml of solvent (I) or (II) after removing the pressure. Repeat this step if necessary.

Reduce the collected fraction to a small volume by evaporation in a vacuum oven at 35 °C or in a vacuum rotary evaporator or similar apparatus and then transfer it without loss into a tared beaker, using more solvent (I) or (II).

Evaporate the contents of the beaker in a vacuum oven at 35 °C to constant weight (W). The difference between the two last weights should not exceed 0,01 g. The time difference between the two weighings should be at least 30 minutes.

The percentage of non-aromatic constituents by weight (A) is given by the following formula:

A= W/W1*100

where W1 is the weight of the sample.

The difference from 100 is the percentage of aromatic constituents absorbed by the silica gel.

6. Accuracy of the method

Repeatability:5 %.

Reproducibility: 10 %.

7. Procedure 2 (chromatography column 2)

Preparation of the sample solution: dissolve approximately 0,9 g (exactly weighed) of the sample in 2,5 ml of n-pentane (I). If the sample is insoluble in n-pentane, dissolve it in cyclohexane and the determination is performed using cyclohexane (II) instead of n-pentane (I).

Pack the chromatography column (chromatography column 2) with the previously activated silica gel, up to about 2,5 cm from the upper glass bulb, by carefully tamping the contents of the column with a vibrator so as not to leave any channels. Then insert a plug of glass wool in the top of the silica gel column.

Pre-moisten the silica gel with 45 ml of solvent (I) or (II), and apply a pressure of air or nitrogen from above until the upper surface of the liquid reaches the top of the silica gel.

Carefully release the pressure inside the column and pour over it approximately 0,9 g (exactly weighed expression with 2 decimals) of sample dissolved in 2,5 ml of solvent (I) or (II), then rinse out the beaker with another 2,5 ml of solvent (I) or (II), and pour this also over the column.

Apply the pressure progressively while allowing the liquid to flow in drops from the bottom capillary tube of the column at the approximate rate of 1 ml/min and collect this liquid in a 250 ml flask.

When the level of the liquid containing the substance to be separated falls to the surface of the silica gel, carefully remove the pressure once more and add 57,5 ml of solvent (I) or (II), re-apply the pressure immediately and bring down the level of the liquid to the surface of the silica gel while collecting the eluate in the same flask as before.

Before the level of the liquid containing the substance to be separated falls to the surface of the silica gel, check the eluate using FT-IR for the presence of aromatics. If the eluate contains only aliphatic hydrocarbons, add again 12,5 ml of solvent (I) or (II) after removing the pressure. Repeat this step if necessary.

Reduce the collected fraction to a small volume by evaporation in a vacuum oven at 35 °C or in a vacuum rotary evaporator or similar apparatus and then transfer it without loss into a tared beaker, using more solvent (I) or (II).

Evaporate the contents of the beaker in a vacuum oven at 35 °C to constant weight (W). The difference between the two last weights should not exceed 0,01 g. The time difference between the two weighings should be at least 30 minutes.

The percentage of non-aromatic constituents by weight (A) is given by the following formula:

A= W/W1*100

where W1 is the weight of the sample.

The difference from 100 is the percentage of aromatic constituents absorbed by the silica gel.

8. Accuracy of the method

Repeatability: 5 %.

Reproducibility: 10 %.

Chromatography column 1

Chromatography column 2

Melt down, whilst constantly stirring, approximately 100 g of naphthalene in a porcelain crucible with a capacity of about 100 cm3. Introduce about 40 cm3 of the melted substance into a preheated ‘Shukoff’ flask so that it is three-quarters filled. Insert a thermometer, graduated in tenths of a degree, through a cork stopper, arranging the mercury bulb in the centre of the liquid. When the temperature has fallen almost to the crystallising point of the naphthalene (around 83 °C), induce crystallisation by continuous agitation. As soon as crystals begin to form, the column of mercury will generally stabilise and then start to fall again. The temperature at which the mercury stabilised and remained static for a certain time is noted and this temperature is taken to be the crystallising point of the naphthalene, after correction to allow for the part of the mercury column outside the flask.

For a mercury thermometer, this correction is taken as being:

where ‘n’ is the number of graduations of the mercury column outside the flask, ‘t’ is the noted temperature and ‘t′’ the mean temperature of the part of the mercury column that is outside the flask. ‘t′’ can be determined approximately with an auxiliary thermometer the bulb of which is placed at mid-height of the part of the column that is outside the flask. A capillary-tube thermometer ensures very high precision.

The ‘Shukoff’ flask illustrated below is a glass receptacle with double walls, the space between which is evacuated: