DE1177270B - Process for the separation of straight-chain paraffins from hydrocarbon oils - Google Patents

Description

Process for the separation of straight-chain paraffins from hydrocarbon oils The claimed process relates to the separation of straight-chain paraffins from paraffinic hydrocarbon oils with the help of molecular sieves and the production improved dewaxed oils. It is characterized by the fact that the at least partially liquid oils at about 300 to 500 ° C together with a gas or steam from top to bottom through a porous moving or non-moving layer of solid particles of a molecular sieve (pore diameter about 5 Å) with a volume ratio of at least 8.5 1 gas per liter of oil and from the molecular sieve an oil with reduced Subtracts content of straight-chain paraffins.

Lubricating oil distillates can expediently be used as paraffin-containing oils Solvent treated, in particular incompletely dewaxed lubricating oil distillate or Residual lubricating oil fractions are used. The space velocity at which the paraffin-containing oil is passed through the molecular sieve, is preferably 0.5 to 2 vol / vol / hour and that of the gas 43.5 to 174 1 per liter of oil.

It is known that certain zeolites adsorb normal paraffins selectively. They are therefore usually referred to as "molecular sieves". These molecular sieves have a practically uniform pore diameter of about 5 Angstrom units. The rate of adsorption increases as the molecular weight of the hydrocarbons increases away.

The treatment with the molecular sieves can be carried out in batches which is usually impractical from a technical point of view. One can sorption in a usual way Perform the chromatography column in the liquid phase. Dewaxing works better of oils, if the paraffin-containing oil is passed through a molecular sieve fixed bed from top to bottom leads with a sufficiently powerful gas or gas operated in the same direction Steam flow so that the oil passes through the bed in the form of a film over the molecular sieve particles runs. The dewaxing can be carried out with larger grains than with the chromatographic method, so it will be a greater speed of the oil flow achieved, with a good separation of the paraffin components from the Oiling becomes possible.

The oils dewaxed with molecular sieves speak more strongly Pour point lower than oils, which, as usual, are the same or even lower Pour point were dewaxed.

Suitable zeolites are e.g. B. in the article »Zeolites as Absorbens and Molecular sieves "by R. M. Barrer," Annual Reports on the Progress of Chemistry for 1944 ", Vol. 61, pp. 31-46, London (1945).

The molecular sieve is used in the claimed process (trickle phase) in the form of lozenges or irregularly shaped particles (mean diameter 1.6 to 6.4 mm or more) of practically uniform size.

The adsorbent is placed in a fixed bed or a fluidized bed, this slowly by continuously or intermittently adding fresh and Decrease in used adsorbent is renewed at opposite ends.

The liquid oil is with the adsorbent together with an inert Brought into contact with steam or gas, e.g. B. with nitrogen, hydrogen, carbon dioxide and light hydrocarbon gases such as methane, ethane or propane.

The oil itself can also be a fraction from the gasoline or Lenelt oil boiling range which evaporates at the temperature and pressure in the sorption zone.

Asphalt oils are used in a known manner with liquid propane deasphalted and placed in the sorption zone at low pressure after preheating, whereby a substantial part of the propane evaporates.

In order to make the contact quickly, the temperature in the According to the invention, the sorption zone is at least 300.degree. At 600C C the Sorption properties of the molecular sieve (not destroyed, but at 450 ° C and higher, the treated oil is easily decomposed. 300 to 400 C. generally preferred, 500 C is valuable with some oils.

The pressure applied in the contact bed can vary from 0.1 to 100 ata; the most suitable are pressures between 1 and 10 ata.

The contact speed, expressed as the volume of liquid oil per bulk volume of the adsorbent per hour, is expediently about 0.5 to 2 vol./vol./hour. The range from 0.5 to 1 vol / vol / hour is preferred. Higher speeds are permitted as long as the draining oil is still practically free of normal paraffin is. Lower speeds are not required as long as the distance is the normal paraffin is sufficiently complete.

The ratio of inert gas to feed oil is expediently at about 43.5 to 174 liters of gas per liter of oil. The gas to oil ratio can be low, z. B. be about 8.5 1 gas per liter of oil, as long as it is sufficient to a vapor phase to maintain in the voids between the particles of the adsorbent, sP that the flow of liquid passes through the adsorbent as a thin film. If necessary, can even higher speeds can be used.

If from the feed oil under the working conditions a lighter one Component of the oil partially evaporated, must be the total ratio of the gaseous sufficient to the liquid fluid in the cavities between the particles Maintain vapor phase. Only small amounts are needed, e.g. B. 100 / o of the oil remain in the liquid phase.

The regeneration of the adsorbent can be carried out in a known manner, for. B. by Burning out with air at 400 to 500 ° C. The so developed Heat can be used to heat up fresh oil for another contact bed, which is switched to adsorption.

The adsorbate can be desorbed and recovered by a low molecular weight liquid straight chain hydrocarbon conducts the sorbent.

F i g. 1 of the drawing shows a schematic representation of the preferred Implementation of the claimed method. From two sorption containers used alternately 11 and 12 with a fixed layer, one, 11, is in operation, while the other, 12, is regenerated or filled. F i g. 1 further shows the heater 14, the product separator 15, a gas circulation pump, heat exchanger and piping. Just for the description important valves and pumps are shown.

A paraffin-containing starting oil enters via line 16, is im Heat exchanger 18 preheated by exhaust gas from the regeneration, further in the heater 14 heated and then passes through line 19 in line 20, in the valve 21 open is, in container 11. At the same time, inert gas passes after heating in 14 from the line 28 via line 22, in which valve 24 is open, into container 11. All of the inert gas can enter the system through line 25 with heat exchanger 26. It will, however preferred to recover inert gas from the product separator 15 and in the circuit to lead through line 29 with pump 30.

When the container 11 is switched to adsorption, there are valves 34 in line 32 and valve 66 in line 65 closed. Line 32 connects to an air source for regeneration, and line 65 is used to remove Regeneration exhaust.

Container 11 is equipped with a perforated plate 35 near the bottom, which carries the fixed bed of the sorbent 37. To the pressure of the sorbent to be reduced to this document, one or more additional ones are further above Conditions provided. The container is on top with a cone manifold 36 for entering Oil equipped.

The ratio of length to diameter of the fixed bed is at least 5: 1, preferably more than 10: 1. The part of the oil that flows down near the wall is deflected inward by troughs 38 and tubes 39 to improve contact.

The gas entering through line 22 flows through the adsorbent bed, mixed with the oil, down where it is from the bottom of the container via line 40 with open valve 41 is withdrawn.

It then passes through lines 42 and 43 with cooler 44 to the separator 15, from which liquid products are withdrawn via line 45. Inert gas passes through line 29 and pump 30 are recirculated or withdrawn through line 46.

The coolant supplied through line 16 can be used as the coolant in the cooler 44 Serve starting oil.

While adsorbing into container 11, container 12 becomes the same can be built, regenerated.

Valve 51 in line 50 and valve 54 in line 52 are closed. The regeneration air goes through line 55, heat exchanger 56, heater 14 and the Lines 58 and 50 through valve 60 into container 12. At the beginning of regeneration the oxygen concentration in the regeneration glass is appropriately kept low. z. B. by partially opening the valve 54 in inert gas line 52 when the inert gas in line 28 is not flammable until the desired mixture is achieved. The oxygen serves to burn off unremoved oil and sorbed solid paraffin from the adsorbent. The resulting gas mixture leaves the container through lines 61 and 64. The exhaust gas is expediently used as a heating medium in exchangers 56, 18 and 26 and then withdrawn from the system. In the event of further contact with the molecular sieve, the inert gas must first be dried.

The end of the separation is determined by determining the pour point certainly. In the case of known oils, the amount per working cycle can be determined through routine tests to be determined in advance. After the required amount of oil has been treated, it becomes a valve 21 closed. Valve 24 is left open a little longer to allow adherent oil remove. Valve 41 is then closed and valve 66 is opened. Valve 24 can be completely or partially closed. The regeneration air is passed through the container Valve 34 and the exhaust gases are withdrawn through line 65. During the switchover of container 11 from sorption to regeneration becomes container 12 switched from regeneration to sorption by opening valve 54 to remove inert Admit gas and valve 60 closes to interrupt its flow of oxygen. Then valve 62 is closed and valve 69 is opened. Oil is supplied, and the Sorption cycle begins.

Example 1 A chromatographic column (length to diameter about 10: 1), which can be heated externally to the desired temperature and could hold on to this. In Experiment 1, the column contained particles of one mesh size from 20 to 170 and 200/0 clay binder, the temperature was 3000 C.

The starting oil was a distillate made from East Texas and Louisiana crude oils with a viscosity of 9.15 cSt at 540 C and 3.51 cSt at 990 C, a medium one Molecular weight of 339 and a pour point of 270 C used that of solvent refining had been subjected.

The adsorbent had a lozenge shape of 1.6 mm in diameter. Run 1 gave poor dewaxing, its results are in the table 1 and shown as curve B of FIG. 2 shown.

Table I. attempt 1 1 2 1 3 1 4 procedure Chromatographic | Trickle phase Adsorbent Sieve 5A I sieve 5A sieve 5A I sieve 5A Particle size ... 1.6 mm lozenges 1.6 mm lozenges 1.6 mm lozenges 1.6 mm lozenges Temperature, 0 ° C. ... . 295 to 345 375 to 425 375 to 425 350 to 375 Space velocity per hour (fluid) ... . . . . . . . . 0.4 1 1 1 Gas velocity, liters per liter of oil - 105 260 105 Pour point, 0 ° C Starting oil. .. 27 Dewaxed oil (Weight percent of the sieve) 5 -4 -15 i 15 -23 15 +4 -15 - 12 - 18 20 t4 - -12 - 25 +7 - -9 27 - - +2 - 30 +10 -9 - - 32 +13 +21 - 35 +18 + +21 - 37 - +27 40 45 Runs 2 and 3 were carried out according to the method of the invention with a liquid film maintained on the particles of the adsorbent and vapor in the voids between the particles. The starting oil was the same as in experiment 1. The experiments differed only in the speed of the gas flow, which was 105 1 per liter of oil in experiment 2 and 2601 per liter of oil in experiment 3.

One column (length to diameter 18.7: 1) was filled with 1.6 mm lozenges from molecular sieve mass with a mesh size of 20 to 170 with 200/0 clay as a binder filled and placed in a heater that keeps them at the desired temperature held.

This fluctuated in different parts of the world Shift and during different periods of the test between 375 and 4950 C. Liquid starting oil and nitrogen were fed to the top of the column at fixed rates. The runoff was collected and the pour point determined for samples. The results are shown in Table 1. The results of experiments 2 and 3 can can be represented by a single curve (curve C in Fig. 2).

When comparing Experiments 2 and 3 with Experiment 1 in Table I or the curve C with curve B in Fig. 2 shows that the trickle phase of experiments 2 and 3 gives a more complete and clean dewaxing than chromatographic Treatment. The pour points of the tests 2 and 3 won Oils are 8 to 11G C lower than the first partial amounts from experiment 1.

Example 2 To the influence of the temperature in the trickle method investigate, experiment 4 was carried out in the same way as experiment 2 of example 1, the temperature being held at 350 to 3750 ° C instead of 375 to 4250 ° C. The first 5 weight percent oil portion based on the screen mass had one Pour point of 23 ° C, the next portions up to about 15% had pour points of - 180 C, and the subset of 220 / o had a pour point of 90 C. In this Case, lowering the temperature had the effect of producing a de-waxed Allowed oil with an even lower pour point than the oil from experiment 2.

Example 3 Trials 5 to 7 were like Trials 2 and 3 of the example 1 carried out using a heavy starting oil (middle distillate). It comes from a Califomia crude oil and had a pour point of 210 C. Experiment 5 was at 350 to 375: C. Trial 6 at 335 to 3550 C and Trial 7 at 300 to 3800 C. In experiment 5, over 3900/0 oil, based on adsorbent, obtained with a total pour point of 70 C, in experiment 6 over 250% with -7 to - 10 and in experiment 7 over 200 ovo oil with -7 and - 10 The effectiveness of an addition of 0.5 weight percent technical pour point depressant based on polyalkymethacrylate to various oils which have been treated according to the claimed process explained by the illustrations below.

In Experiment 2 of Example 1, the pour point depressant was added first the portion of the product which had a pour point of - 150 C, this one down to - 370 C. The pour point of the second portion, which was -90 ° C, became also reduced to -37 ° C. by adding a pour point depressant. Of the The pour point of the entire sample was lowered from 70 ° C to - 340 ° C.

Equally good results were obtained when using other pour point depressants based on polyallyl methacrylate or on alkylated polycyclic aromatics.

An addition of 0.5% by weight of one made of acrylic ester resins Pour point depressant, as sold under the trade name "Acryloid 150" becomes a 100 grade neutral oil, produced by solvent extraction and solvent dewaxing of a 100% distillate from a mid-continent crude oil, lowered the pour point from -123 C to 340 C; around the same pour point of 340 C by adding the same A lot of pour point depressants can be achieved with an oil of the same origin, however dewaxed using the process according to the invention was only one dewaxing required up to a pour point of 90 C. An addition of 0.50 / o of a pour point depressant to a mixture of a distillate oil and 6 percent by weight of a residual lubricating oil, either in the usual way or with Dewaxed with the aid of the method according to the invention resulted in a much lower pour point in the latter case than in the former, although the pour point of the mixture itself (without lowering agent) is in the latter Case was higher. The results can be found in Table II.

Table II Pour point, 0 ° C oil + 10.5 weight Ö1 percent Pour point humiliating 250 neutral oil, distillate ..... - 12 - 29 Dewaxed in the usual way residual lubricating oil (B) - 12 1 Residue lubricating oil, dewaxing ned by molecular sieve (C) - 12 - Mixtures of A + 6 weight percent B. -12 1 21 A + 6 weight percent C. 4 1 29 Oils which can be treated by the claimed process are hydrocarbon oils which contain solid normal paraffins with about twenty or more carbon atoms per molecule.

The starting oil for this process can initially be prepared by known processes be deasphalted.

If necessary, the oil can also be used after treatment with molecular sieves deasphalt.

Suitable oils contain 50 to 1000 / o normal paraffins, the concentration the total paraffin should not be more than 25 percent by weight of the oil, preferably do not exceed 2 percent by weight.

Claims (3)

Claims: 1. Process for separating straight-chain paraffins from hydrocarbon oils with the aid of molecular sieves, d a d u r c h g e - indicates, that the at least partially liquid oils at about 300 to 5000 C together with a gas or steam moving from top to bottom through a porous or not moving layer of solid particles of a molecular sieve (pore diameter about 5 A) with a volume ratio of at least 8.5 liters of gas per liter of oil The molecular sieve removes an oil with a reduced content of straight-chain paraffins. 2. The method according to claim 1, characterized in that as paraffin-containing Oils lubricating oil distillates or treated with solvents, especially incomplete dewaxed lubricating oil distillate or residual lubricating oil fractions are used will. 3. The method according to claim 1 and 2, characterized in that the paraffin-containing oil through the molecular sieve at a space velocity of 0.5 to 2 vol / vol / hour and the gas at a rate of about 43.5 to 174 liters each Liter of oil is passed.