Solid hydrotreatment catalyst, its synthesis and its use in the deoxygenation process of triglycerides
Patent Information
- Application Number
- EP2024817425
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-11-08
- Filing Date
- 2024-11-07
- Publication Date
- 2025-10-01
AI Technical Summary
Existing catalysts for producing green diesel from triglycerides face challenges such as the need for solvents, limited active catalytic phase, and suboptimal calcination temperatures, leading to inefficiencies and environmental concerns.
A bulk hydrotreatment catalyst synthesis method involving separate calcination of nickel, molybdenum, and aluminum salts to form oxides, followed by mixing and grinding without solvents, allowing for a higher active catalytic phase and optimal calcination temperatures.
The method enables a more efficient and sustainable production of green diesel by increasing the active catalytic phase, optimizing calcination conditions, and eliminating solvent use, resulting in higher yields and lower environmental impact.
Smart Images
Figure IB2024061013_15052025_PF_FP_ABST
Abstract
Description
[0001] "SOLID HYDROTREATMENT CATALYST , ITS SYNTHESIS AND ITS USE IN THE DEOXYGENATION PROCESS OF TRIGLYCERIDES"
[0002] CROSS-REFERENCE TO RELATED APPLICATIONS
[0003] This Patent Application claims priority from Italian Patent Application No . 102023000023556 filed on November 8 , 2023 , the entire disclosure of which is incorporated herein by reference .
[0004] TECHNICAL FIELD
[0005] The present invention concerns a solid hydrotreatment catalyst , a method for the synthesis thereof and a deoxygenation process of triglycerides by means of the solid catalyst .
[0006] In particular, the present invention is advantageously, but not exclusively, applied in the production of hydrocarbons useful for the combustion of diesel ( green diesel ) engines .
[0007] STATE OF THE ART
[0008] Due to the ascertained non-renewability of fossil fuels , and consequent impact on the environment , in recent years research has focused on the development and production of green diesel .
[0009] Green diesel is produced by processing triglycerides of biological origin, such as animal fats or vegetable or algal oils , and functions like a traditional fuel . In fact , its chemical-physical properties are very similar to conventional diesel and it can therefore be used in fossil diesel engines without requiring any modi fication to the engine .
[0010] More speci fically, green diesel is composed mainly of saturated hydrocarbons with a number of carbon atoms from Cis to C18 •
[0011] The main advantages of green diesel are , in particular, a 30% mean reduction in polluting emissions and the fact that it does not leave residues, maintaining the engine in perfect operating condition.
[0012] Furthermore, green diesel is very stable, non-corrosive, has a high calorific value and a good cetane number, in addition to a density and cloud point lower than both bio-diesel (FAME) and fossil diesel.
[0013] Another advantageous aspect of the production of green diesel is the possibility of industrial utilization of a product which is difficult to dispose of (for example used vegetable oil) , with obvious advantages in economic and environmental terms .
[0014] The production of green diesel entails the catalytic treatment, with hydrogen, of triglyceride-based biomasses, such as vegetable oils.
[0015] The catalysts used in the production of green diesel are a combination of three oxides according to the following formula x(NiO) y(Mo03) z (A12O3) .
[0016] So far, the solid catalysts typically used are catalysts supported on solids such as, for example, AI2O3 and produced via processes that entail the use of solvents in which the precursors of nickel and molybdenum oxides are dissolved. Once the precursors have bound to the support (AI2O3) , the solvents have to be removed by subsequent operations which necessarily involve expenditure of time and money at the expense of productivity. Furthermore, by law, the solvent effluents have to undergo a purification process before they are discharged into the environment, and this obviously requires further expenditure of resources, time and money.
[0017] Another drawback relative to the above supported catalysts concerns the limitation in terms of quantity of usable active catalytic phase . The active catalytic phase is generated by reduction of the nickel and molybdenum oxides deposited in the catalyst , and the maximum quantity that can be deposited on the support is the quantity that completely covers the surface of the support ( aluminum oxide ) . In fact , once the surface of the support has been covered by the active catalytic phase , further additions may not adhere to the surface of the catalyst or may not increase the surface heterogeneous catalytic activity .
[0018] Therefore , in the above supported catalysts , the maj ority phase is necessarily the support phase (AI2O3 ) even though the active catalytic phase is the one obtainable by reduction of the nickel and molybdenum oxides .
[0019] Another drawback concerns the need for the nickel and molybdenum oxide precursors to be soluble in the solvents to be used . Usual ly, to guarantee the solubility of these precursors , other compounds have to be used, for example to correct the pH of the solution, with the obvious resulting problems .
[0020] Furthermore , once the precursors of the active nickel and molybdenum phases have bound to the substrate , the calcination phase is carried out to obtain the respective oxides . The calcination temperature necessarily has to be the same for both the precursors , which means that it is not possible to choose the optimal temperature for the single precursor . As will be immediately obvious to a person skilled in the art , the use of a calcination temperature higher than the optimal temperature could produce thermal stress which could also entail sintering phenomena or the formation of inadequate crystalline phases , to the detriment of the ef ficiency of the catalyst overall .
[0021] DISCLOSURE OF THE INVENTION The need was therefore felt for catalysts for the production of green diesel with technical characteristics such as to overcome the above drawbacks of the known art .
[0022] The subj ect of the present invention is a synthesis method of a bulk hydrotreatment catalyst for the production of green diesel ; said synthesis method being characteri zed in that it comprises in succession :
[0023] - a calcination phase , wherein nickel salts , molybdenum salts and aluminum salts , separately from one another, undergo a calcination treatment to obtain respective oxides ;
[0024] • for said nickel salts the calcination phase comprising heating to a temperature between 250 and 600 ° C for a time between 7 and 15 h;
[0025] • for said molybdenum salts , the calcination phase comprising heating to a temperature between 300 and 400 ° C for a time between 7 and 15 h;
[0026] • for said aluminum salts the calcination phase comprising heating to a temperature between 400 and 600 ° C for a time between 7 and 15 h;
[0027] - a cooling phase , wherein the nickel , molybdenum and aluminum oxides deriving from the calcination phase are brought , separately from one another, to a temperature between 10-30 ° C in a humidity condition between 30- 0% RH; a milling phase , wherein said nickel , molybdenum and aluminum oxides deriving from said cooling phase are mixed with one another to form a mixture of oxides , which undergoes grinding; said mixture of oxides comprising 10 to 30% by weight of nickel oxide , 30 to 80% by weight of molybdenum oxide and 10 to 40% by weight of aluminum oxide .
[0028] The synthesis method as defined above , in addition to not entailing the use of solvents , allows the presence of an active catalytic phase to a signi ficantly greater extent than the similar supported catalysts and, at the same time , guarantees use of the speci fic calcination temperature for forming each of the oxides considered.
[0029] Furthermore, the possibility of increasing the active catalytic phase as reported can allow both increased effectiveness of the catalyst and, therefore, increased yield of the deoxygenation reaction, and lower work temperatures, thus benefiting productivity. Preferably, said mixture of oxides comprises 15 to 25% by weight of nickel oxides, 50 to 70% by weight of molybdenum oxide and 15 to 25% by weight of aluminum oxide.
[0030] Preferably, said calcination phase provides for a heating rate between 1 and 10°C / min.
[0031] Preferably, said cooling phase comprises
[0032] - a first cooling sub-phase, wherein the oxides coming from the calcination phase are brought to a temperature between 150-101°C;
[0033] - a second cooling sub-phase, wherein the oxides coming from the first cooling sub-phase are brought to a temperature between 10 - 30°C.
[0034] Preferably, said milling phase is carried out by means of a ball mill.
[0035] Another subject of the present invention is a solid hydrotreatment catalyst produced with the synthesis method of the present invention and having the formula x (NiO) y(MoOs) z (AI2O3) with x between 10% and 30% by weight, y between 30% and 80% by weight, and z between 10% and 40% by weight; preferably x is between 15% and 25% by weight, y is between 50% and 70% by weight, and z is between 15% and 25% by weight.
[0036] Another subject of the present invention is a synthesis method of saturated hydrocarbons from triglycerides of vegetable origin; said synthesis method comprising a catalytic deoxygenation phase, wherein in a hydrocarbon solvent, triglycerides of vegetable origin and the catalyst subject of the present invention are subjected to a temperature between 250°C and 350°C in hydrogen atmosphere at a pressure which at ambient temperature is between 20 and 60 bar; the weight % of the catalyst with respect to the oil being between 20 and 1.
[0037] Preferably, the solvent / oil weight ratio is between 1 and 20.
[0038] Preferably, the synthesis comprises a preliminary activation phase, wherein the solid catalyst subject of the present invention is treated at a temperature between 300 and 900°C in the presence of a reducing gas, preferably H2, at a pressure which at ambient temperature is between 40 and 80 bar for a time between 1 and lOh.
[0039] EMBODIMENT OF THE INVENTION
[0040] Embodiment examples are given below for a better understanding of the present invention, with the aid of the attached figure which shows an ATR-FTIR spectrum of the reagents and the deoxygenation reaction products of vegetable oils subject of the present invention.
[0041] EXAMPLES
[0042] - Synthesis of the solid catalyst -
[0043] The procedure for synthesis of the solid catalyst according to the present invention is described below.
[0044] The separate preparation of the NiO, AI2O3 and M0O3 oxides was carried out by performing calcination of the respective salts in an electric muffle furnace.
[0045] In particular, 38.0078 g of Ni (NOs)2 *6H2O were subjected to a temperature of 500°C for a period of 12 hours, obtaining 9.7551 g of NiO; 37.1655 g of Al (NO3) 3* 9H2O were subjected to a temperature of 550°C for a period of 12 hours, obtaining 5.3385 g of AI2O3; 12.3124 of (NH4 ) 6M07O24* 4H2O were subjected to a temperature of 350°C for a period of 12 hours, obtaining 10.0592 g of M0O3. In the above calcination phase, the heating rate was 5°C / min.
[0046] Once the calcination phase was completed, the oxides produced were left to cool in the muffle furnace until reaching a temperature of 120°C.
[0047] Subsequently, the oxides were removed from the muffle furnace and left to cool to the ambient temperature of 23°C in a dryer with humidity of 10% RH.
[0048] Once cooled, the oxides were mixed and ground by means of a ball mill having zirconia bowl and balls (Planetary Monomill "Pulverisette 6") . The mixture of oxides undergoing mixing had the following composition expressed in weight %: 18.5% NiO, 19% AI2O3 and 62.5% M0O3.
[0049] The mixing was carried out in the complete absence of solvent, at a rotation speed of 300 rpm and for a milling time of 30 min. The ball / oxide mass ratio was 8.3:1.
[0050] The catalyst thus obtained was examined under electron microscope (SEM) to morphologically and topologically evaluate the success of the synthesis. It was ascertained that an intimate mixing had been obtained at the level of single solid particle of the various elements introduced with the calcined oxides, and the absence of any undesired element.
[0051] - Catalytic deoxygenation of triglycerides of vegetable origin
[0052] To verify the catalytic activity of the catalyst produced as described above, catalytic deoxygenation tests of alimentary rapeseed oil were carried out. Before carrying out the catalytic deoxygenation tests, the catalyst was activated by means of pre-reduction performed in a batch reactor (make: PARR) for 4 hours at 320°C and initial pressure at ambient temperature of H2 equal to 60 bar.
[0053] The tests were carried out in a batch reactor (make: PARR4590, controller model PARR 4848) in hydrogen atmosphere at a starting pressure at ambient temperature equal to 40 bar.
[0054] The tests were performed by varying the process conditions relative to (i) temperature, (ii) catalyst / oil ratio and (iii) reaction time.
[0055] At the end of each test, the catalyst was filtered, and the reaction product was recovered and analyzed, after derivatization, via GC-FID (gas chromatography with flame ionization detection) , GC-MS (gas chromatography - mass spectrometry) and FT-IR ATR (attenuated total reflectance Fourier-transform infrared) spectroscopy.
[0056] The GC-FID analysis allowed identification of the compounds present in the reaction product and estimation of their percentage distribution. The GC-MS allowed the identification of unknown compounds not identifiable by GC-FID. Lastly, the IR (FT-IR ATR) spectroscopy allowed an estimate to be obtained of the conversion of the triglycerides and fatty acids into hydrocarbons .
[0057] Table I shows the process conditions of nine catalytic deoxygenation tests carried out.
[0058] TABLE I
[0059] Table II shows the results obtained from the nine tests of Table I .
[0060] TABLE II *Fatty Acid Methyl Ester
[0061] As can be seen from the data shown in Table II, the catalyst subject of the present invention is effective in the deoxygenation reaction of the triglycerides.
[0062] Again from Table II it can be seen that the parameters relative to the percentage of presence of the catalyst, the temperature and the reaction time affect the diesel conversion and yield. It will therefore be possible to improve the yield of the deoxygenation reaction by appropriately intervening on the three parameters referred to above.
[0063] It is extremely important to note that with the bulk catalyst subject of the present invention the majority of the hydrocarbons produced are of the type Cis-Cis and, therefore, extremely interesting for the preparation of green diesel.
[0064] In particular, the conditions of the test 1 lead to a conversion percentage of 100. In fact, in the case of the test 1, a completely hydrocarbon reaction product was obtained composed 86.9% of linear hydrocarbons C15-C18 (suitable for combustion in diesel engines) . In particular, the reaction yield in linear hydrocarbons C15-C18 ("Diesel Yield") with respect to the initial mass of oil used was 64.4%.
[0065] The attached figure shows the FT-IR ATR spectra relative to the oil used as reagent (rapeseed oil) and the reaction product obtained in test 1. From a comparison of the spectra shown in the figure, it can be seen that in the spectrum relative to the reaction products, the peak corresponding to the carbonyl group of the esters (1745 cur1) , the peak relative to the carbonyl of the free fatty acids (1710 cur1) and the peaks in the zone 1400-800 cur1are not present. The only observable signals are those of the vibrations of the C-H bonds (saturated hydrocarbons) . From these observations it can be deduced that the reaction product obtained consists exclusively of saturated hydrocarbons, as confirmed by table IT .
[0066] The present invention permits the realization of a bulk catalyst x (NiO) y(Mo03) z (AI2O3) for the production of green diesel (a) without using solvents, with the resulting advantages in terms of productivity, (b) being able to vary the quantity in % of the relative oxides without limitations due to the support and to its maximum coverage or solubility of the precursor salts in the solvent used for the impregnation procedure, (c) being able to obtain each oxide in the respective optimal conditions, thus improving the effectiveness of the catalyst overall. Furthermore , among the advantages it should be mentioned that the bulk catalyst according to the present invention also allows participation of the aluminum oxide in the catalysis . Otherwise , in the supported catalysts , since the aluminum oxide constitutes the support and is therefore covered, it cannot contribute to the catalytic activity .
[0067] The synthesis of the catalyst in the absence of solvent guarantees greater sustainability with respect to the synthesis methods of the known art , since no liquid waste is produced and, furthermore , it entails shorter process times , according to the principles of Green Chemistry and Green Engineering . In the light of the above , the products of the deoxygenation reaction according to the present invention are characteri zed by a higher sustainability rate in the holistic balance of a cradle-to-gate , cradle-to-grave , or cradle-to- cradle ( in the case of circular use ) li fe cycle assessment .
Claims
CLAIMS1 . A method of synthesis of a bulk hydrotreatment catalyst for the production of green diesel ; said synthesis method being characteri zed by comprising in succession :- a calcination phase , in which nickel salts , molybdenum salts and aluminum salts , separately from each other, undergo a calcination treatment to obtain respective oxides ;• for said nickel salts the calcination phase involves heating to a temperature between 250 and 600 ° C for a time between 7 and 15 h;• for said molybdenum salts the calcination phase involves heating to a temperature between 300 and 400 ° C for a time between 7 and 15 h;• for said aluminum salts the calcination phase involves heating to a temperature between 400 and 600 ° C for a time between 7 and 15 h;- a cooling phase in which the nickel , molybdenum and aluminum oxides deriving from the calcination phase are brought , separately from one another, to a temperature between 10 - 30 ° C in a humidity condition between 30- 0% RH; a milling phase , in which said nickel , molybdenum and aluminum oxides deriving from said cooling phase are mixed with one another to form a mixture of oxides , which is subj ected to grinding; said mixture of oxides comprising 10 to 30% by weight of nickel oxide , 30 to 80% by weight of molybdenum oxide and 10 to 40% by weight of aluminum oxide .2 . The method of synthesis of a solid hydrotreatment catalyst according to claim 1 , characteri zed in that said mixture of oxides comprises 15 to 25% by weight of nickel oxide , 50 to 70% by weight of molybdenum oxide and 15 to 25% by weight of aluminum oxide .3 . The method of synthesis of a solid hydrotreatment catalyst according to claim 1 or 2 , characteri zed in that saidcalcination phase involves a heating rate between 1 and 10 °C / min .
4. The method of synthesis of a solid hydrotreatment catalyst according to one of the previous claims, characterized in that said milling step takes place using a ball mill.
5. A solid hydrotreatment catalyst produced according to one of the previous claims and having formula x (NiO) y(MoOs) z (AI2O3) with x between 10% and 30% by weight, y between 30% and 80% by weight, and z between 10% and 40% by weight.
6. The solid hydrotreatment catalyst according to claim 5, characterized in that x is between 15% and 25% by weight, y is between 50% and 70% by weight, and z is between 15% and 25% by weight .
7. A method of synthesis of saturated hydrocarbons from triglycerides of biological origin; said synthesis method comprising a catalytic deoxygenation step, in which, in a hydrocarbon solvent, triglycerides of biological origin and said catalyst according to claim 5 or 6 are subjected to a temperature between 250°C and 350°C in a hydrogen atmosphere at a pressure which at ambient temperature is between 20 and 60 bar.
8. The synthesis method according to claim 7, characterized in that the weight % of the catalyst with respect to the oil is between 20 and 1.
9. The synthesis method according to claims 7 or 8, characterized by the fact of comprising a preliminary activation phase, in which said solid catalyst according to claim 5 or 6 is treated at a temperature between 300 and 900°C in the presence of a reducing gas at a pressure at ambient temperature between 40 and 80 bar for a time between 1 andlOh.
10. The synthesis method according to claim 9, characterized in that said reducing gas is H2.