PROCESS FOR THE PRODUCTION OF BIO-OIL FROM BIOMASS

Abstract

Process for the production of bio-oil from biomass comprising the following steps: (a) feeding a biomass to a liquefaction reactor, said biomass having a protein content higher than or equal to 1% by weight, preferably ranging from 5% by weight to 50% by weight, with respect to the weight (dry weight) of said biomass, a lipid content higher than or equal to 1% by weight, preferably ranging from 5% by weight to 60% by weight, with respect to the weight (dry weight) of said biomass, a pH higher than or equal to 4, preferably ranging from 4.5 to 10; (b) subjecting said biomass to liquefaction operating at a temperature ranging from 220 C. to 350 C., preferably ranging from 230 C. to 310 C., even more preferably ranging from 240 C. to 300 C., at a pressure higher than the vapour pressure of water at the temperature in which said liquefaction is carried out, for a time ranging from 30 minutes to 300 minutes, preferably ranging from 50 minutes to 270 minutes, obtaining a mixture comprising an oily phase consisting of bio-oil, a solid phase, a gaseous phase and an aqueous phase. The bio-oil (or bio-crude) thus obtained can be advantageously used as such, or, after optional upgrading treatments, in the production of biofuels or biocombustibles that can, in turn, be used as such or in a mixture with other fuels, for motor vehicles. Or, said bio-oil (or bio-crude) can be used in a mixture with fossil fuels (fuel oil, coal, etc.) for the generation of electric energy or heat.

Claims

1. A process for producing bio-oil from biomass, the process comprising: (a) feeding a liquefaction reactor with a biomass having a protein content higher or, equal to 1% by weight, with respect to the weight (dry weight) of said biomass, a lipid content higher or equal to 1% by weight, with respect to the weight (dry weight) of said biomass, a pH higher than or equal to 4; and (b) subjecting said biomass to liquefaction operating at a temperature ranging from 220 C. to 350 C., at a pressure higher than a vapor pressure of water at a temperature in which said liquefaction is carried out, for a time ranging, from 30 minutes to 300 minutes, thereby obtaining a mixture comprising an oily phase consisting of bio-oil, a solid phase, a gaseous phase and an aqueous phase.

2. The process according to claim 1, wherein said liquefaction is carried out at a pressure ranging from 25 bar to 110 bar.

3. The process according to claim 1, further comprising: performing a preliminary process comprising homogenization, grinding or sizing, prior to said liquefaction.

4. The process according to claim 1, wherein said biomass is wet and/or said biomass has a water content higher than or equal to 50% by weight, with respect to the total weight of said biomass.

5. The process according to claim 1, herein the biomass has a protein content ranging from 5% by weight to 50% by weight with respect to the weight (dry weight) of said biomass.

6. The process according to claim 1, wherein the biomass has a lipid content ranging from 5% by weight and 60% by weight with respect to the weight (dry weight) of said biomass.

7. The process according to claim 1, wherein the biomass has a pH ranging from 4.5 to 10.

8. The process according to claim 1, wherein;the liquefaction is carried out at a temperature ranging from 240 C. to 300 C.

9. The process according to claim 1, wherein the liquefaction carried out for a time ranging from 50 minutes to 270 minutes.

10. The process according to claim 2, wherein the liquefaction is carried out at a pressure ranging from 30 bar to 100 bar.

11. The process according to claim 4, wherein said biomass has a water content ranging from 55% by weight to 80% by weight with respect to the total weight of said biomass.

Description

EXAMPLES 1-4

Corrosion Test in the Liquefaction Reactor

[0082] A corrosion test was carried out in the liquefaction reactor.

[0083] For this aim, AISI 304L and AISI 316L steel U-bend test-samples type A were obtained according to the standard ASTM G30-97 (2009). The above test-samples were then smoothed with abrasive paper up to 1,200 grit and U-bent over a diameter of 10 mm by means of a specifically produced punch and mould, again operating in accordance with the above-mentioned standard ASTM G30-97 (2009). Before being bent, the test-samples were initialled, degreased in acetone and ultrasounds and weighed with an analytical balance having an accuracy of 0.1 mg.

[0084] A sample-holder was also produced (shown in FIG. 1 in which the measurements are indicated in mm) to which three pairs of U-bend test-samples obtained as described above, were fixed, at a different height, so as to optionally expose them to different phases produced in the liquefaction reactor, if stratified. The sample-holder with the test-samples was immersed in an autoclave made of Hastelloy C276 having a nominal volume of 1 litre, which forms the liquefaction reactor. 400 g of wet organic fraction of solid urban waste (SUW) previously homogenized by means of a cutting mill were fed into the same autoclave by means of a suitable dosing system: the homogenization allowed a creamy product to be obtained with particles having dimensions lower than 1 mm.

[0085] An aliquot of the homogenized product (6 g) was anhydrified by drying in an oven, under vacuum, at 60 C., in order to determine its dry weight which proved to be equal to 29.9% by weight. The macro-composition of the homogenized product as such and after anhydrification is indicated in Table 1. Table 1 also shows the pH value of said homogenized product.

TABLE-US-00002 TABLE 1 Carbo- Lipids hydrates Proteins Ashes Water Total SUW (%)* (%)* (%)* (%)* (%)* (%)* pH As such 8.9 11.7 7.6 1.6 70.1 100 6.5 Anhy- 29.8 39.3 25.5 5.4 0 100 n.m.** drous *weight % with respect to the total weight of the homogenized product (As such) or with respect to the total weight of the homogenized product after anhydrification (Anhydrous); **not measurable

[0086] After creating an inert atmosphere inside the autoclave by washings with nitrogen, the autoclave was rapidly heated so as to reach the desired internal temperature: the whole unit was maintained at said temperature, for the desired time, after which the maximum pressure reached (P.sub.MAX) was recorded. The temperature, time, maximum pressure (P.sub.MAX) and type of steel of the various tests are indicated in Table 2.

TABLE-US-00003 TABLE 2 Temperature P.sub.MAX Time Material test- Example (%) (bar) (minutes) samples 1 240 44 54 AISI 316L 2 240 40 250 AISI 316L 3 300 90 96 AISI 316L 4 240 40 263 AISI 304L

[0087] At the end, the autoclave was left to cool and when room temperature (25 C.) had been reached, the residual pressure was measured in order to calculate the incondensable gases that had developed during the test.

[0088] The residual pressure was then discharged by depressurization and the discharged gaseous phase was sampled in a bag in order to subject it to analysis. Said gaseous phase was analyzed separately by means of gas-chromatographic techniques, proving to be equal to 6%-12% by weight with respect to the weight (dry weight) of the initial biomass (i.e. homogenized product fed), in relation to the liquefaction conditions indicated in Table 2. The analysis showed that the gaseous phase was composed for over 95% in moles of carbon dioxide, <2% in moles of carbon monoxide and hydrogen, <1% in moles of hydrocarbons, such as methane, ethane, ethylene, propane, propylene and butenes, <1% in moles of other gases such as hydrogen sulfide, methyl-mercaptan, ethyl-mercaptan, dimethylsulfide, carbonyl sulfide and other sulfur compounds not identified, in addition to traces of ammonia. The concentration of oxygen optionally present in the gas phase is always below the threshold detectable by the gas-chromatograph (0.1% in moles).

[0089] The autoclave was washed with nitrogen and subsequently opened to recover the test-samples that were treated manually to eliminate any optional solid residues remaining on them and on the sample-holder, then washed with ethyl acetate and further cleaned with acetone and ultrasounds.

[0090] After the above treatments, the test-samples were subjected to the following analyses: [0091] weight loss of the test-sample: the test-sample was weighed before (the two test-samples were weighed in each position) and after the test (results obtained reported in Table 3); [0092] calculation of the corrosion rate calculated as indicated hereunder (results obtained reported in Table 3). [0093] The corrosion rate was calculated according to the following formulae: [0094] exposed surface of the test-sample S (expressed in cm.sup.2) corresponding to the total side surface, minus the area of the holes and plus the inner side area of the holes:

[00001]$S=l.Math.l_a.Math.2+\left(l+l_a\right).Math.s.Math.2-4.Math.\frac{d^2}{4}.Math.+2.Math.s.Math.d.Math..Math.$

wherein: [0095] l=length of test-sample equal to 8.0 cm; [0096] l.sub.a=width of test-sample equal to 2.0 cm; [0097] s=thickness of test-sample equal to 0.25 cm; [0098] d=holes diameter equal to 1.0 cm; [0099] =constant equal to 3.14; [0100] corrosion rate v (expressed in m/year):

[00002]$v=\frac{\mathrm{DP}.Math.365.Math.\left(\mathrm{days}.Math.\text{/}.Math.\mathrm{year}\right).Math.24.Math.\left(\mathrm{hours}.Math.\text{/}.Math.\mathrm{day}\right).Math.10000.Math.\left(\mathrm{.Math.m}.Math.\text{/}.Math.\mathrm{cm}\right)}{1000.Math.\left(\mathrm{mg}.Math.\text{/}.Math.g\right).Math.\mathrm{density}.Math.S.Math.t}.Math.\left(\mathrm{.Math.m}.Math.\text{/}.Math.\mathrm{year}\right)$

wherein: [0101] DP=weight loss of the test-sample (mg); [0102] density=density of the test-sample (g/cm.sup.3); [0103] t=exposure time (h); [0104] S=exposed surface of the test-sample (expressed in cm.sup.2) calculated as described above.

[0105] It should be pointed out that the corrosion rates indicated in Table 3, which are lower than 20 m/year, are lower than the values normally tolerated. There are in fact corrosion resistance tables, used as guidelines for selecting metallic materials in the presence of chemical compounds and in relation to the temperature, which are defined on the basis of reliable laboratory data available and to be considered as a recommendation basis, as indicated, for example, on the internet site http://www.tempco.it/wp-content/uploads/2012/12/corrosione.pdf. In said tables, stainless steels are considered as being resistant to uniform corrosion in liquid or wet environments if the corrosion rate does not exceed 0.1 mm/year. In particular, the corrosion resistance is classified as follows: [0106] excellent: materials with a corrosion rate lower than 0.13 mm/year; [0107] good: materials with a corrosion rate ranging from 0.126 mm/year to 0.5 mm/year; [0108] poor: materials with a corrosion rate ranging from 0.5 mm/year to 1.26 mm/year.

[0109] Furthermore, in order to verify the depth of the attacks present, the test-sample of Example 1, positioned at an intermediate height, was sectioned along the longitudinal axis, the ends were then cut and it was englobed in hot polyester resin. It was then polished with metallographic cards and subsequently with diamond paste, until it had a mirror surface. A thin layer of gold (50 nm) was deposited on the test-sample thus prepared to allow it to be observed with a Scanning Electronic Microscope (SEM) under high vacuum: FIG. 2 shows how these defects have extremely small dimensions, less than 10 m.

[0110] It should be noted that no breakage or presence of cracks due to corrosion under stress was observed in any of the U-bend test-samples subjected to the above tests (Examples 1-4): said evaluation was carried out by observation with an optical viewer up to 50 magnifications.

TABLE-US-00004 TABLE 3 Example - Initial weight of Weight variation of Corrosion Position of test-sample test-sample rate test-sample (g) (mg) (m/year) 1 -high 25.89911 1.64 9.5 position 25.93416 1.45 8.4 1 - medium 25.71319 n.d. n.d. position 25.40102 1.66 9.6 1 - low 25.69001 1.90 11.0 position 23.31027 2.63 15.2 2 - high 25.39030 8.16 10.2 position 25.63747 8.00 10.0 2 - medium 25.28610 3.47 4.3 position 25.15848 2.15 2.7 2 - low 25.22749 3.26 4.1 position 24.04689 3.13 3.9 3 - high 25.31946 2.87 9.4 position 24.74700 3.56 11.6 3 - medium 25.33724 4.11.sup.(*.sup.) n.d. position 25.94607 2.79.sup.(*.sup.) n.d. 3 - low 25.91014 9.50.sup.(*.sup.) n.d. position 25.71712 10.73.sup.(*.sup.) n.d. 4 - high 25.79420 9.89 11.8 position 24.76584 6.99 8.3 4 - medium 25.74405 2.72 3.2 position 25.95623 4.39 5.2 4 - low 25.40773 4.39 5.2 position 26.16785 9.89 11.8 .sup.(*.sup.)dirty test-sample; n.d.: not determined

EXAMPLE 5

Corrosion Test in the Liquefaction Reactor by Means of the Slow Strain Rate Technique

[0111] The slow strain rate technique was used as a rapid technique to highlight the onset conditions of stress corrosion cracking due to the presence of chlorides (Chloride Stress Corrosion CrackingCSCC) and/or hydrogen sulfide (Sulfide Stress Corrosion CrackingSSCC).

[0112] The test was carried out according to the standard ASTM G129-00 (2013). In this respect, the test-sample to be evaluated was subjected to traction and deformed until to breakage. The test was carried out in both an inert atmosphere, and in an aggressive atmosphere, with a strain rate equal to 10.sup.5 s.sup.1, which was such as to allow the synergic interaction between environment and stress, which is at the basis of stress corrosion phenomena. Various parameters were obtained from the test deriving from a comparison of the tests carried out in an aggressive environment with respect to those carried out in an inert environment (in particular, in air, considered as being a non-aggressive environment and therefore inert, for steel of the series AISI 300). In this case, the parameters obtained were: elongation at break and reduction of area, which were measured on the test-sample after breakage of the test-sample itself.

[0113] The elongation at break in percent (A %) was calculated as follows:

(A %)=[(l.sub.fl.sub.o)/l.sub.o].Math.100

wherein: [0114] l.sub.o represents the initial length of the test-sample subjected to traction; [0115] l.sub.f represents the final length (after breakage) of the test-sample subjected to traction.

[0116] The reduction area in percent (S %) was calculated as follows:

(S %)=[(S.sub.oS.sub.u)/S.sub.o].Math.100

wherein: [0117] S.sub.o represents the initial section of the test-sample subjected to traction; [0118] S.sub.u represents the breakage section of the test-sample subjected to traction.

[0119] The design of the test-samples was made on the basis of the above standard ASTM G129-00 (2013) (as shown in FIG. 3, in which the measurements indicated are in mm).

[0120] The autoclave used for the test was produced in Hastelloy C and had an internal volume of about 500 ml. 430 g of homogenized product having the macro-composition and pH indicated in Table 1, were charged into the autoclave and put in contact with the test-sample: test-sample in stainless steel AISI 304L [Example 5 (a)] and test-sample in stainless steel AISI316L [Example 5 (b)].

[0121] After verifying the sealing of the autoclave with compressed air at 6 bar and bringing it to atmospheric pressure, the autoclave was rapidly heated so as to reach an internal temperature of 250 C. and consequently, a pressure due to the vapour pressure of the compounds in addition to the formation of incondensable gases, equal to about 70 bar. The traction of the test-sample (low strain rate test start) was initiated when said temperature had been reached and set so as to obtain a constant strain rate equal to 10.sup.5 s.sup.1: after about 6 hours under this condition, the breakage of the test-sample was observed.

[0122] At the end, the autoclave was left to cool and, when a temperature of 60 C. had been reached, the residual pressure was discharged by depressurization. The autoclave was then washed with nitrogen and subsequently opened to recover the test-sample which was treated manually to eliminate any optional solid residues remaining on it.

[0123] In order to have a comparison with the inert atmosphere, the tests were carried out under the same operating conditions of temperature and strain rate also in air, at atmospheric pressure.

[0124] The elongation at break values in percent (A %) and the reduction of area in percent (%), for the above test-samples are indicated in Table 4. Table 4 also indicates the embrittlement indexes calculated as specified hereunder.

[0125] The mixture obtained comprising bio-oil, aqueous phase and solid phase remaining inside the autoclave was subjected to separation by demixing between water and bio-oil to recover the aqueous phase and with the subsequent addition of ethyl acetate to solubilize the bio-oil to enable it to be separated from the remaining aqueous phase and solid phase which was insoluble in said solvent. The suspension obtained was filtered on paper and the solvent/bio-oil mixture obtained was subjected to evaporation to recover the bio-oil; the recovered bio-oil was subjected to an analysis protocol to determine the content of the main compounds present as described hereunder in Example 6.

[0126] The test-samples were washed with ethyl acetate to remove the products selectively anchored on their surface: the ethyl acetate obtained from said washing was analyzed as described hereunder in Example 7.

TABLE-US-00005 TABLE 4 Homogenized Air product Embrittlement (250 C.-40 bar) (250 C.-40 bar) index.sup.(*.sup.) Strain rate 10.sup.5 10.sup.5 (s.sup.1) (S %) AISI 304L 63 (air) 17 [Example 5 (a)] 0.73 AISI 316L 63 (air) 34 [Example 5 (b)] 0.46 (A %) AISI 304L 17 (air) 11 [Example 5 (a)] 0.35 AISI 316L 17 (air) 13 [Example 5 (b)] 0.23 .sup.(*.sup.)calculated as follows: 1 - [(S %)example/(S %)air]; 1 - [(A %)example/(A %)air]

EXAMPLE 6

Characterization of the Bio-Oil

[0127] As indicated above, the bio-oil obtained in Example 5 was subjected to characterization by means of a complete analytical protocol using various analytical techniques: said techniques are described in the article of Chiaberge S. et al., Characterization of Bio-oil from Hydrothermal Liquefaction of Organic Waste by NMR Spectroscopy and FTICR Mass Spectrometry, ChemSusChem (2013), Vol. 6, pages 160-167. This protocol allowed the main types of compounds present to be identified. Among the main compounds, fatty acids were identified as primary products deriving from the liquefaction, fatty acid amides and alkylaromatic compounds containing heteroatoms [for example, nitrogen (N), oxygen (O)] as secondary products deriving from the liquefaction: the results obtained are indicated in Table 5.

[0128] The bio-oil was also subjected to analysis of the acidity by determining the TAN number (Total Acid Number), according to the standard ASTM D664-11A, obtaining a value of 45.

TABLE-US-00006 TABLE 5 Aliphatics Steranes and sterols 1.2% 53.9% paraffins and olefins 1.2% alkylpyrroles 0.9% alkylpyrrolidones 1.4% alkylcyclopentanones 0.1% alkylfurans 2.3% alkylpiperidines 0.9% Free fatty acids (FAs) 23.9% Fatty acid esters 0.4% Fatty acid amides 21.0% Cyclic fatty acid amides 0.6% Alkylaromatics alkylbenzenes <0.1% 46.1% alkylindenes <0.1% alkylindanes <0.1% alkylindols 2.3% alkylbenzimidazoles <0.1% alkylindanones <0.1% alkyl benzofurans <0.1% alkyltetrahydronaphthalenes <0.1% alkyldihydronaphthalenes <0.1% alkylfphenols 0.3% alkyltrimellitates 0.4% alkylhydroxypyridines <0.1% Aromatic fatty acid amides 0.3% Alkylaromatic compounds containing N, O 42.5% % indicates the weight % with respect to the total weight of the bio-oil recovered.

EXAMPLE 7

Analysis of the Ethyl Acetate Obtained from the Washing of the Test-Samples of Example 5

[0129] The ethyl acetate obtained from the washing of the test-samples of Example 5 was subjected to complete analytic protocol, using various analytical techniques: these techniques are described in the article of Chiaberge S. et al., Characterization of Bio-oil from Hydrothermal Liquefaction of Organic Waste by NMR Spectroscopy and FTICR Mass Spectrometry, ChemSusChem (2013), Vol. 6, pages 160-167.

[0130] The main products present in the ethyl acetate, that account for over 60% by weight with respect to the total weight of the organic substances solubilized therein, proved to be amides belonging to the list indicated in FIG. 4.