WO2008114033A2

WO2008114033A2 - Biogasoline

Info

Publication number: WO2008114033A2
Application number: PCT/GB2008/001013
Authority: WO
Inventors: Geir Remo Fredriksen; Trond Myrstad
Original assignee: Statoilhydro Asa; Campbell, Neil
Priority date: 2007-03-21
Filing date: 2008-03-20
Publication date: 2008-09-25
Also published as: US20100083566A1; GB2447684B; GB0705435D0; WO2008114033A3; CN101720349A; BRPI0809136A2; CA2681394A1; EP2134813A2; GB2447684A

Abstract

A process for the preparation of a biogasoline component comprising: (I) obtaining at least one biooil and, if necessary, liquefying the biooil component; (II) adding the bio-oil in liquid form to a FCC unit along with at least one mineral oil; (III) cracking the components added to the FCC unit to form at least a bio-LPG fraction and a bio-naphtha fraction; (IV) alkylating or catalytically polymerising at least part of the bio-LPG fraction; and (V) combining at least a part of the product of step (IV) with at least a part of the bio-naphtha fraction to form a bio-gasoline component.

Description

Biogasoline

This invention relates to a process for the formation of biogasoline by the fluid catalytic cracking (FCC) of biooils, in particular fish oils, in combination with mineral oil. The process maximises the bio content of the fuel by ensuring that both the LPG and naphtha fraction of the cracked material are used in the fuel.

There is increasing World concern about climate change and hence carbon dioxide emissions, hi Europe at least, measures are now being taken at the highest level to try to reduce carbon dioxide emissions in all walks of life. This means a heavier reliance on renewable energy sources such as solar and wind power, increasing taxation on energy inefficient products and more investment in harnessing the power of the sea. A further quickly developing field is biofuels, especially for vehicles.

The biofuels directive of 2003 (Directive 2003/30) established an indicative target value of 5.75 % market share for bio-fuels at the end of 2010. The reference value is based on the energy content of the fuel, and each member state is to set national targets. In the Energy and Climate Package and the related Renewable Energy Roadmap published on 10 January 2007, the European Commission proposes a minimum binding 10% target of biofuels for vehicle use to be reached in the EU by 2020.

The use of flexifuel vehicles, which run on alcohol, in particular ethanol (and also methanol), are already well known. Ethanol can be produced from sugar cane and is frequently used in blends with gasoline to form a biofuel (E5, E85) . Methanol is however toxic and is not an ideal material for the mass market, its use currently being confined therefore to racing vehicles.

Fuel manufacturers have therefore looked at other bio compounds as fuel additives and are now considering the manufacture of biogasoline and biodiesel from biooils. In US 2006/0186020, a process for the mild hydrocracking of vegetable oil is described in which the vegetable oil is mixed with a mineral oil and cracked to form a diesel component.

Other manufacturers have considered the fluid catalytic cracking of biomaterial to form gasoline components. In US 5,233,109 a process for cracking plant oil, animal oil or natural rubber is described and in US 4,300,009, the conversion of plant material to gasoline using zeolites in a cracking process is discussed. Both these documents utilise a 100% bio feed to the cracking unit but for commercial operation, it will be essential to combine the bio material with a conventional mineral oil component. The biomass will simply not be available for 100% biofuel.

A process for cracking mineral oil mixed with vegetable oil was proposed by Petrobras in Brazilian Patent Application PI 8304794 in 1983. A similar process scheme has also more recently been suggested by UOP. OMV has also reported results from cracking of mineral oil mixed with vegetable oils. Vegetable oil contains long chain fatty acids (in the triglyceride form and as free fatty acids) and these chains can be cracked in a fluid catalytic cracking unit to form shorter hydrocarbon chains and hence potentially a biogasoline component.

A major problem, however, with biofuels such as biogasoline is that availability of biomaterial to incorporate into the fuel is limited. To incorporate a significant portion of biocomponent into all gasoline used in the World would put an enormous strain on the World's natural resources. To grow the necessary plant material would require large amounts of land and might therefore involve the further destruction of forest across the globe. As the destruction of forest is a major contributor to climate change, to destroy forest to create biomass for biofuel would be counter productive. It is vital therefore that biomass available for biofuel production ends up in the fuel and is not wasted.

The inventors have realised that cracking bio-oils alone or in presence of a mineral oil produces bio-naphtha as well as bioLPG. The inventors have further realised that the resulting bioLPG component can be post treated, and then combined with the bionaphtha fraction to form biogasoline. In this way, over 50% of the biomaterial added to the cracker can form part of the gasoline.

Moreover, the inventors have surprisingly found that marine bio-oils can be cracked successfully in the same manner as vegetable oils in a FCC unit in combination with mineral oil. Whilst the use of vegetable oils in a FCC unit in combination with mineral oil has been described, the use of a marine oil is new and forms a further aspect of the invention. Marine oils may contain high levels of heavy metals. Some of these heavy metals are poisonous to the catalysts conventionally used in a FCC unit so the use of " marine oils has not been suggested in the art, potentially for this reason. The inventors have realised that FCC units processing at least some heavy oil, i.e. atmospheric or vacuum resids already have most of these metals present in the feed to the FCC unit. Such FCC units are therefore already using FCC catalysts which can inherently tolerate certain amounts of heavy metals. The inventors have further realized that when blending a marine oil, e.g. less than 50 %, more preferably less than 30 % marine oil, which inherently contains heavy metals, with a FCC feed which also contains such metals, the level of heavy metals in the blend will not change significantly. The present invention therefore has particular relevance in FCC units processing at least some heavy oil, i.e. atmospheric or vacuum resid.

Furthermore, the inventors have surprisingly found that marine oils can be successfully cracked without any pre-treatment. Since pretreatment is potentially expensive this is an important advantage. and not one which the skilled man would expect. Untreated marine oils may well contain a variety of potential catalyst poisons and undesirable materials, which could affect cracking.

Thus, viewed from one aspect the invention provides a process for the preparation of a biogasoline component comprising:

(I) obtaining at least one biooil, e.g. fish oil, and, if necessary, liquefying the biooil component;

(II) adding the bio-oil in liquid form to a FCC unit along with at least one mineral oil, e.g. a mineral oil containing heavy metals;

(III) cracking the components added to the FCC unit to form at least a bio-LPG fraction and a bio-naphtha fraction;

(IV) alkylating or catalytically polymerising at least part of the bio-LPG fraction; and

(V) combining at least a part of the product of step (IV) with at least a part of the bio-naphtha fraction to form a bio-gasoline component.

Viewed from another aspect the invention provides a process for the preparation of a biogasoline component comprising: (I) obtaining at least one marine oil and, if necessary melting the marine oil such that it is in liquid form;

(II) adding the marine oil in liquid form to a FCC unit along with at least one mineral oil , e.g. a mineral oil containing heavy metals;

(III) cracking the components added to the FCC unit to form at least a bionaphtha fraction which is a biogasoline component.

Viewed from another aspect the invention provides a biogasoline containing a biogasoline component made by the processes as hereinbefore described.

Viewed from another aspect the invention provides the use of marine oil to form biogasoline.

By biogasoline is meant gasoline containing a biologically derived component. The process of the invention provides a biogasoline component. This component can be added to other biogasoline or non biocomponents to form a biogasoline or could be used by itself as a biogasoline.

Naphtha is defined as the fraction bf the cracked material containing C5+ hydrocarbons having a boiling point up to 221 °C. Bionaphtha is a biocomponent containing naphtha.

By LPG (liquefied petroleum gas) is meant hydrocarbons with three or four carbon atoms; such as propane, propene, butanes and butenes. BioLPG is a biocomponent containing LPG.

By dry gas is meant hydrogen and hydrocarbons with one or two carbon atoms; such as methane, ethane and ethene.

By marine oil is meant those oils which are derived from marine sources such as fish, algaes cultivated in ponds or in bioreactors, micromarine organisms (krill and the like) or marine mammals such as seals. In a preferred embodiment the marine oil is a fish oil. Whilst it is preferred if the marine oil derives from a sea based organism, in this invention, the term marine oil is intended to cover freshwater sources of fish oils as well.

The biooil used in the invention may be a plant oil, animal oil or marine oil and can be obtained from any convenient source. These materials are readily available. Suitable plant oils include vegetable oils (soy oil, rape seed oil), fruit oils (olive oil) or oils of plants such as the sunflower. Animal oils could derive from cows or pigs and the like. Preferably, however, the oil derives from a marine source such as seals, algaes, krill or especially fish, most especially sea fish.

It will, of course, be possible to use a mixture of biooils in the cracking process. Mixtures of two different plant oils could be used or a vegetable oil mixed with a marine oil.

Biooils can also be classified in relation to their free fatty acid content (FFA). Preferably, the FFA content of the biooils used in the present invention may range from 1.5 to 40%, e.g. 2 to 30%, especially 5 to 20 % .

The bio-oil added to the FCC unit needs to be in liquid form. If the bio-oil (or mixture of biooils) is already in liquid form then it can be added without any pretreatment at all. Some biooils may however be solids and will therefore require liquefying, e.g. melting before addition to the FCC unit. Melting is achieved simply be heating the oil above its melting point which could be around 50-60°C.

Other than a possible melting step, it is an advantageous feature of the invention that the when the biooil is a marine oil it does not need any pretreatment at all. It can therefore be used in its raw state straight after isolation from the marine organism. That no pretreatment of the feed is highly surprising because a naturally occurring marine oil is likely to impurities which are potentially damaging to an FCC process.

The bio-oil is added to the FCC unit along with at least one mineral oil component. By mineral oil component is meant a fraction of crude oil. Preferably the mineral oil is a gas oil, e.g. straight run gas oil, vacuum gas oil, coker gas oil, atmospheric residua, vacuum residua and residual fractions from other refining processes.

The mineral oil and biooil components can be added to the FCC unit in separate conduits or can be mixed before entry to the FCC unit, hi this latter embodiment, mixing preferably occur after any melting step.

Bio-oil contains in most cases less sulphur than the mineral oil; especially if the mineral oil contains a heavy oil component, e.g. atmospheric or vacuum resids. Thus, a blend of bio-oil and mineral oil will, most likely, contain less sulphur than the mineral oil itself. As a result, the sulphur levels in the cracked products will be reduced, and less sulphur removal in sulphur removal processes downstream the FCC unit will be necessary.

Biooil also in most cases contains less nitrogen species than the mineral oil, especially if the mineral oil contains a heavy oil portion such as atmospheric or vacuum resids. A blend of bio oil and mineral oil will then contain less nitrogen species than the mineral oil itself. Basic nitrogen species are the main source of NOx emissions from a FCC unit, and with less basic nitrogen species in the feed, the NOx emissions will be reduced. In addition basic nitrogen species are known to cause reversible deactivation of the FCC catalyst, and with less such species in the feed, less deactivation of the catalyst will occur.

The relative amounts of all bio-oil components to mineral oil can vary over a wide range and may be governed by the availability of biooil starting material. Whilst it is envisaged therefore that a useful biogasoline component can be made with many different oil ratios, in commercial application it is likely that the amounts of biooil will be 50 wt% or less, preferably 20 wt% or less, e.g. 15 wt % or less, especially 10 wt% or less relative to the mineral oil. A minimum of 1 wt% could be used.

Heavy mineral oils such as atmospheric or vacuum resids will typically contain metals. The main metallic contaminants are nickel (Ni) and vanadium (V), but heavy mineral oils will typically also contain traces of other metals, such as calcium (Ca), potassium (K), iron (Fe), copper (Cu), sodium (Na), etc.

The concentration of metals in a heavy mineral oil feed can vary greatly depending on the source of that feed, but concentrations of Ni and V up to 100 parts per million (ppm) are not uncommon. The inventors have determined that modern FCC catalysts are able to tolerate concentrations of Ni and V at least up to 10 ppm without unacceptable levels of catalyst deactivation or other negative effects.

Marine oils also contain heavy metals as these are a natural components of marine oils. The inventors have realised that the metals present in marine oils typically are the same metals as those typically present in heavy oils. The inventors have further realised that the concentration of the metals present in marine oils typically are of the same order of magnitude as the concentration of the metals present in heavy oils suitable for catalytic cracking. The addition of a marine oil to the FCC unit along with a mineral oil will therefore have negligible effect on the amount of heavy metals present. The inventors have therefore determined that the FCC process still works well without catalyst deactivation.

The operation of a FCC unit is well known in the art and is carried out throughout the World and will only be briefly discussed herein.

Catalytic cracking is an established and widely used process in the petroleum refining industry for converting heavy oils of relatively high boiling point to more valuable lower boiling products including gasoline and middle distillates such as kerosene, aviation fuel and heating oil. A preheated feed is normally brought into contact with a hot cracking catalyst that is in the form of a fine powder, typically with a particle size of 10-300 μm for the desired cracking reactions to take place. Catalyst temperatures of around 500 to 550°C are usual. The feed temperature may be around 200⁰C although in the present invention it is important that the temperature of the biooil feed is kept below a temperature which might cause the biooils to degrade or react in some fashion.

During cracking, coke is deposited on the catalyst and this results in a loss of activity and selectivity. The coke is removed by continuously removing the deactivated catalyst from the cracking reactor and oxidatively regenerating it by contacting it with air in a regenerator. The combustion of the coke not only removes the coke but also serves to heat the catalyst to temperatures appropriate for the cracking reaction. The catalyst is continuously circulated from the reactor to regenerator and back to the reactor. Zeolite catalysts are routinely employed.

As noted above, certain biooils, in particular marine oils contain heavy metals which are poisons for zeolite catalysts. The inventors have realised that FCC units processing at least some heavy oil, i.e. atmospheric or vacuum resids already are using FCC catalysts which can tolerate certain amounts of heavy metals. Cracking of marine oils will therefore occur without serious loss of activity.

The cracked mixture which leaves the FCC unit passes to a fractionation tower where it is separated into various fractions including bioLPG and bionaphtha. The operation of a fractionation tower is well known in the art and is carried out in refineries across the globe. The skilled man is therefore aware of how to operate such a tower. The amount of each fraction formed will vary considerably depending on the nature of the biooil and mineral oil feed but the bionaphtha fraction preferably forms at least 30 wt% of the cracked material, preferably at least 40 wt%.

The bioLPG fraction preferably forms at least 10 wt%, more preferably at least 15 wt% of the cracked material.

Other components and fractions of the cracked material include water, carbon dioxide, carbon monoxide, dry gas, LCO (light cycle oil) and HCO (heavy cycle oil). .

It will be appreciated therefore that catalytic cracking of a biooil will produce a significant amount of water whilst catalytic cracking of a mineral oil feed will not. The inventors have realised that water is present in the FCC unit under normal operations as stripper steam, in some cases as lift gas, and in some cases for removing salt depositions in the fractionation tower. The water produced by catalytic cracking of bio oil will therefore not give any processing problems.

The inventors have further realised that carbon monoxide and carbon dioxide is produced when cracking a bio oil. When cracking a mineral oil, these components are not present in the FCC products; only in the regenerator offgas. The inventors have surprisingly found that the cracking reaction proceeds without loss of activity in the presence of these materials. Whilst carbon dioxide can be released to the environment, CO is highly poisonous and must be treated before release. The inventors have realised this can be achieved if the carbon monoxide is flared along with the dry gas which is generated by the cracking reaction. Any CO present will then be converted to CO₂.

In step (IV) of the process of the invention at least a part of the bioLPG component formed during cracking is alkylated to bioalkylate or catalytically polymerised to biopolymerate, which can be used in a biogasoline.

Alkylation is a known process in which low molecular weight compounds, preferably n-butylene, are mixed in the presence of a catalyst such as hydrofluoric acid or sulphuric acid with isobutane. The product is called alkylate and is composed of a mixture of high-octane, branched-chain paraffmic hydrocarbons. Alkylate is a premium gasoline blending stock because it is low in aromatics and sulphur content, low RVP and good octane numbers (RON and MON). For example, isooctane results from combining butylene with isobutane and has an octane rating of 100 by definition. There are other products in the alkylate, so the octane rating . will vary accordingly. By alkylating the bioLPG fraction a biogasoline blending component is formed which is capable of increasing considerably the octane number of the gasoline.

As an alternative to alkylation, at least a part of the bioLPG component can be subjected to catalytic polymerisation. This involves the combination of two olefin molecules, such as butenes or propenes to form a high-octane olefmic blendstock.

For either alkylation or catalytic polymerisation, in may be necessary to separate the bioLPG into the components preferred for alkylation (C4 components) or catalytic polymerisation in which case only a part of the bioLPG fraction may be treated in this step. Often only the olefinic components of the bioLPG can be converted to bionaphtha and depending on the nature of the bioLPG produced, olefins may form a third to two thirds, preferably 50% to 66% of the bioLPG.

Also, propylene, which often forms part of the LPG component, is a valuable olefin in its own right and may be separated from the bioLPG for use in polymerisation rather than for conversion to a bionaphtha. The invention can therefore provide a biopropylene monomer and therefore biopolypropylene materials

Depending on the nature of the bioLPG formed 25% to 33% of the bioLPG may be converted to bionaphtha.

The treated LPG can then be combined with at least part of, preferably all of the bionaphtha made in step (III), and used in gasoline. In this way over 50 wt% of the original biooil containing feed can be utilised in gasoline fuel. It will be appreciated that the bionaphtha/bioLPG mixture can act as gasoline on its own but more usually this will be combined with gasoline blending components from other parts of a refinery, e.g. combined with reformate from catalytic reforming or isomerate.

It has surprisingly been found that biogasoline made using marine oil in combination with mineral oil possess a higher RON than the mineral oil alone. This is a very important result as higher RON fuels are becoming essentiaHn the market place to satisfy newer engine specifications and emission requirements. A fuel with higher RON means less upgrading of mineral oil is required. It is believed that the increase in RON is caused by an increase in aromatic components in the material. The RON of the biogasoline component made by the process of the invention may be 0.5% or more higher than that of the RON of the biogasoline component formed from the mineral oil alone.

The biogasoline of the invention is preferably used in land based vehicles as opposed to aircraft.

To utilise still more of the bio material, the bioLCO component of the cracked material can be used in biodiesel. LCO is defined as the fraction boiling at 221 to 344°C and is therefore suitable for use in diesel directly.

The invention will now be described in relation to the following non limiting examples and figures.

Brief Description of the Figures

Figure 1 shows the content of aromatics in the naphtha fraction as a function of conversion from MAT experiments.

The conversion as a function of the catalyst to oil ratio for different blends of FCC feed and fish oil from FCC pilot riser experiments is shown in Figure 2. Figure 3 depicts a simplified processing scheme. Mineral oil is mixed with biooil through conduit (1). After preheat (2), the mixed feed enters FCC unit (3). The cracked mixture passes to fractionation tower (4) for separation to bionaphtha in conduit (5) and bioLPG in conduit (6). The bioLPG is alkylated in unit (7) and mixed with the bionaphtha which is optionally hydrotreated in unit (8). The resulting blend forms a bio gasoline component. Optionally, from the fractionation tower (4), bio LCO is separated in conduit (9). This bio LCO is optionally hydrotreated in unit (10) and can be used as a bio diesel blending component.

Example 1. Catalytic cracking of fish oil in MAT

Cracking of fish oil was demonstrated in a Micro Activity Test (MAT) reactor. Testing in MAT is a well known method within the field of catalytic cracking. The fish oil was obtained from Scanbio, Lysøysund, Norway, and corresponded to what is denoted raw fish oil, i.e. no refinement of the fish oil has been done. Some properties of the fish oil is given in Table 1.

Table 1: Properties of raw fish oil

In the MAT experiments two different feeds were tested and compared:

• FCC feed (atmospheric resid) with no addition of fish oil

• Fish oil with no addition of FCC feed The FCC feed used in the experiments was a North Sea atmospheric residue with the following properties:

Table 2: Properties of atmospheric resid

Density 0,9275 kg/1

Conradson Carbon Content 3,0 wt%

Sulphur 0,404 wt %

Nickel 1,6 ppm

Vanadium 2,0 ppm

Sodium 0,6 ppm

Nitrogen (basic) 420 ppm

The FCC catalyst used in the experiments was NEKTOR 766 ST supplied by GRACE Davison; a catalyst designed to tolerate metals present in the FCC feed. Cyclic Propylene Steaming (795°C, 1400 ppm Ni, 2200 ppm V) was used to deactivate the catalyst prior to the tests.

Interpolated yields from the tests, compared at the same conversion (77.5 %) are shown in Table 3.

Table 3: Yields (in wt-%) for the different products and product fractions.

As can be seen from Table 3; the dry gas yield (C₂-) increases due to the formation of CO and CO₂ when fish oil is cracked. Water is also formed. As a consequence the yields of LPG and naphtha decreases. The naphtha octane number, i.e. RON, increases due an increased aromaticity of the naphtha, (see also Figure 1) In one particular refinery, the naphtha fraction from the FCC unit represents 44 % of the material used to form a gasoline fuel. To obtain a bio part in the gasoline as a whole of 2 %, assuming no bio polymerate or bio alkylate are available, it will be necessary to blend approximately 5.1 % fish oil into the feed to the FCC unit.

Table 4 gives an overview of the estimated changes in the FCC product composition based on the results from Table 3, when blending 5.1 wt% fish oil in the FCC feed (atmospheric resid).

Table 4 : Comparison of yield structure with blending 5.1 wt% fish oil in the FCC feed and without blending fishoil in the FCC feed.

As can be seen from Table 4, only small yield changes are expected if a low amount offish oil; i.e. approximately 10 % or preferably even lower, such as approximately 5 % is processed.

Example 2. Catalytic cracking of blends of fish oil and atmospheric resid in pilot riser

In a continuously operated FCC pilot riser, different blends of the two feeds described in Example 1; fish oil and a North Sea atmospheric residue, were tested. The FCC catalyst used in these tests was an equilibrium catalyst (ECAT) from a FCC unit processing North Sea atmospheric residue.

Figure 2 shows the conversion as a function of the catalyst to oil ratio for different blends offish oil and FCC feed. As can be seen from this figure; blending fish oil into the FCC feed has no significant effect on the conversion.

Interpolated yields from the tests, compared at the same conversion (72.5 %) are shown in Table 5.

Table 5: Yields (in wt-%) for the different products and product fractions.

The results were used to estimate the yield structure when blending 5.1 % fish oil into the FCC feed, as it was don in Table 4. These results are shown in Table 6.

Table 6. Comparison of yield structure with blending 5.1 wt% fish oil in the FCC feed and without blending fishoil in the FCC feed based on results from pilot riser.

As can be seen from Table 6; also when using results from the pilot riser, only small yield changes are expected if a low amount offish oil; i.e. approximately 10 % or preferably even lower, such as approximately 5 % is processed.

Claims

1. A process for the preparation of a biogasoline component comprising:

(I) obtaining at least one biooil and, if necessary, liquefying the biooil component;

(II) adding the bio-oil in liquid form to a FCC unit along with at least one mineral oil;

2. A process as claimed in claim 1 wherein the biooil is a marine oil.

3. A process as claimed in any preceding claim wherein the mineral oil contains heavy metals.

4. A process as claimed in any preceding claim wherein the biooil forms up to 10 wt% of the components added to the FCC unit.

5. A process as claimed in claim 2 wherein the marine oil is used without pretreatment.

6. A process as claimed in any preceding claim wherein the bionaphtha fraction forms at least 40 wt% of the cracked material.

7. A process as claimed in any preceding claim wherein the bioLPG fraction forms at least 10 wt% of the cracked material.

8. A process as claimed in any preceding claim wherein the bioLPG fraction is alkylated.

9. A process as claimed in any preceding claim wherein at least 50 wt% of the biooil containing feed is converted to biogasoline components.

10. A process for the preparation of a biogasoline component comprising:

(I) obtaining at least one marine oil and, if necessary , liquefying the biooil component;

11. A biogasoline containing a biogasoline component made by the processes as hereinbefore described.

12. Use of marine oil to form biogasoline.