TECHNICAL FIELD

The invention relates to nickel, iron dopped tungstated zirconium catalyst and its use to obtain 2-methyl furan from the furfural compound.

BACKGROUND

The present invention relates to the development of a nickel and iron dopped tungstated zirconium catalyst for improving the thermal value and therefore the properties for its potential use as a fuel by removing the high oxygen content of the bio-oil by the hydrodeoxygenation (HDO) method. Hydrodeoxygenation is an important method that is carried out in the presence of a catalyst, in the hydrogen atmosphere, at partially high temperatures (200-400°C), and may include reactions such as deoxygenation (C-0 bond rupture), hydrogenation (hydrogenation of C=O bond and aromatic ring), hydrogenolysis, hydro-cracking, decarboxylation and dehydration and thus provides hydrocarbon from oxygenated compounds.

Although furfural is an extremely reactive compound obtained from biomass pyrolysis, it contains different oxygenated groups due to its aromatic furan ring and aldehyde group attached to this ring. Due to the high octane number and low solubility in water of 2-methyl furan obtained by removing oxygen of furfural in the presence of a catalyst, it is known to be a fuel additive with high potential in standard vehicle driving tests.

Almost all of the catalysts used for the hydrodeoxygenation of furfural in the literature contain noble metals. Liao et al. (2015) show that 2-MF is obtained with high selectivity in the hydrodeoxygenation process of 5-hydroxymethyl furfural (HMF) when nickel and palladium immobilized on carbon support are used as bimetallic. In studies where catalysts such as nickel and cobalt are used instead of noble metals, it is known that it brings along conditions such as the addition of auxiliary chemicals and the formation of by-products in order to suppress the formation of coke. Wang et al. found in their study that they had to add different alcohols to the medium in order to suppress the formation of coke when they used a nickel- dopped catalyst. The main purpose is to obtain 2-methyl furan with 100% selectivity from furfural. Although different catalysts (metal sulfide, metal carbide, metal phosphorus, etc.) used for this purpose, their reusability rates are low due to the low stability of these catalysts. In their study using molybdenum carbide, Lee and colleagues obtained different furan compounds, which are a highly secondary product. Banerjee et al. reported that they also observed C4-C5 products as a by-product, although they converted furfurated high amounts of furan in the presence of boron and nickel-dopped catalysts. Meng et al. in their study in 2020, in which NiZn alloy was used, obtained a high rate (95%) of 2-methyl furan; however, they also reported the formation of tetrahydrofurfuryl alcohol in the medium.

The patent CN112264032A, which is in the state of the art, has explained its use in the furfural hydrodeoxygenation of the NiMo/Zr02 catalyst. However, as mentioned in the said patent, 2-methyl furan selectivity was reported as 94% and catalyst reusability was reported as 86%. As a result, it was aimed to increase the said selectivity and repeatability rate and to realize reactions with lower costs in the studies conducted in the known state of the art.

The main object of the present invention is to provide a catalyst that overcomes the above problems, enabling the said hydrodeoxygenation reactions to be carried out at a lower cost, while achieving higher selectivity and repeatability rates.

BRIEF DESCRIPTION OF THE INVENTION

The main object of the invention is to provide a catalyst with nickel-iron dopped tungstated zirconium (having the formulation NiFe/WOxZrOs) to obtain 2-methyl furan from the furfural compound. Wherein x is less than 3.

In one embodiment of the invention, a production method is provided for the catalyst with the formulation NiFe/WOxZrOs of the invention, comprising the following steps: a. Synthesizing tungstated zirconium, b. Adding nickel and iron metals to tungstated zirconium.

The synthesis of step a. of the method of an embodiment of the invention comprises the following steps: i. adding ammonia to the zirconium oxochloride solution, ii. washing the mixture obtained in step i., iii. application of drying after washing in step ii. and obtaining zirconium hydroxide particles, iv. applying back distillation to the aqueous solution of ammonium meta tungstate with zirconium hydroxide, v. filtering and calcining the solid product obtained in step iv.

In step iv. in step a. in the method of an embodiment of the invention, the ratio of the aqueous solution of the ammonium meta tungstate to zirconium hydroxide is in the range of 2 to 40 by mass, or preferably in the range of 3.2 to 36.8.

In step iv. in step a. in the method of an embodiment of the invention, the back distillation is carried out for 1 to 15 hours, or preferably 2 to 12 hours.

In step v. in step a. in the method of an embodiment of the invention, the calcination process is carried out in the temperature range of 600 to 1000°C, or preferably in the temperature range of 630-970°C.

Step b. in the method of an embodiment of the invention comprises the following steps: i. Adding nickel(ll)nitrate hexahydrate and iron(lll)nitrate nonahydrate to tungstated zirconium in a water-ethyl alcohol medium, ii. sonicating and mixing the solution obtained in step i., iii. removing alcohol and water in the solution from the medium, iv. drying the substance obtained in step iii., v. performing the calcination process.

In step i. in step b. in the method of an embodiment of the invention, the amount of nickel(ll)nitrate hexahydrate is in the range of 3500-10000 mg or preferably 3890-9880 mg.

In step i. in step i. in the method of an embodiment of the invention, the amount of the iron(lll)nitrate nonahydrate is in the range of 1-250 mg or preferably in the range of 1 .24-210 mg.

In step ii. in step b. in the method of an embodiment of the invention, the sonification process is performed for 1 -3 hours. In step ii. in step b. in the method of an embodiment of the invention, the mixing is carried out for 8-12 hours.

In step iv. in step b. in the method of an embodiment of the invention, the drying process is carried out at 100-120°C.

In step v. in step b. in the method of an embodiment of the invention, the calcination process is performed at 400-800°C or preferably 500-700°C.

In one embodiment, the use of the compound with the formulation NiFe/WOxZrOs as a catalyst for obtaining 2-methyl furan from the furfural compound is presented.

BRIEF DESCRIPTION OF THE DRAWINGS OF THE INVENTION

Figure 1 shows XRD patterns of WOx-ZrOs catalyst support material.

Figure 2 shows XRD patterns of Ni-Fe dopped WOx-ZrOs catalysts.

Figure 3A and 3B shows SEM-EDX images of the Ni-Fe dopped WOx-ZrOs catalyst.

DETAILED DESCRIPTION OF THE INVENTION

The main object of the invention is to provide a catalyst with the formulation NiFe/WOxZrOs (nickel-iron dopped tungstated zirconium) to obtain 2-methyl furan from the furfural compound. Wherein x is less than 3.

The said catalyst of the invention in particular catalyzes the hydrodeoxygenation of the furfural compound. As a result of the reaction catalyzed by the nickel, iron-dopped tungstated zirconium (NiFe/WOxZrOs) in the invention, 2-methyl furan is obtained from furfural with 100% selectivity.

In addition to its selectivity, one of the important features of catalysts is their reusability. There are many catalysts with low reusability rates due to low stability in the state of the art. The reusability rate of the catalyst of the present invention is 95% as shown in Table 1 . The criterion determining the reusability rate is the amount of coke produced during the hydrodeoxygenation reaction. Coke formation is prevented during the said reaction with the catalyst of the present invention. This increases the reusability of the catalyst. In one embodiment of the invention, the W/Zr ratio of the catalyst in the said catalyst is in the range of 0.05-0.55 by mass. Thanks to the W/Zr ratio in this embodiment of the invention, the rate of coke formation was reduced to 0.30-0.46% (Table 1). Solvents such as high-cost methanol, ethanol, and isopropanol that can be used during the reaction are also prevented by reducing the coke rate, which is around 20% in the literature, in the present invention. In addition, the hydrodeoxygenation reaction carried out with the catalyst of the invention is carried out at 2 MPa H2 pressure and for 3 hours. Therefore, the conversion of furfural to 2- methyl furan by hydrodeoxygenation is provided at a lower cost compared to the state of the art.

Table 1 - Furfural Transformation Performance of Ni-Fe dopped WOx-ZrO2 catalyst

In one embodiment of the invention, a production method is provided for the catalyst with the formulation NiFe/WOxZrOs of the invention, comprising the following steps: a. Synthesizing tungstated zirconium, b. Adding nickel and iron metals to tungstated zirconium.

The use of catalysts such as nickel and cobalt instead of noble metals, the addition of auxiliary chemicals to suppress the formation of coke, and the formation of by-products in the state of the art. In the production method of the catalyst of the present invention, the addition of nickel and iron metals to tungsten-plated zirconium prevents the use of auxiliary chemicals or the formation of by-products.

The synthesis of step a. in the method of an embodiment of the invention comprises the following steps: i. adding ammonia to the zirconium oxochloride solution, ii. washing the mixture obtained in step i., iii. drying after washing in step ii. and obtaining zirconium hydroxide particles, iv. applying back distillation to the aqueous solution of ammonium meta tungstate with zirconium hydroxide, v. filtering and calcining the solid product obtained in step iv.

In the method in this embodiment of the invention, ammonia is slowly added to the zirconium oxochloride solution to form Zr(OH)4 for the synthesis of the support material (WOxZrOs) until pH=8 at room temperature and then washed until there is no chlorine ion in the medium and the presence of chlorine ion in the medium is controlled by AgNO3 (silver nitrate). After washing, drying is performed in step iii. and then Zr(OH)4 particles are obtained.

In step iv. in step a. in the method of an embodiment of the invention, the ratio of zirconium hydroxide to the aqueous solution of ammonium meta tungstate is in the range of 2 to 40 by mass or preferably in the range of 3.2 to 36.8.

In step iv. in step a. in the method of an embodiment of the invention, the back distillation is carried out for 1 to 15 hours, or preferably 2 to 12 hours.

In step v. in step a. in the method of an embodiment of the invention, the calcination process is carried out in the temperature range of 600 to 1000°C, or preferably in the temperature range of 630-970°C.

Step b. in the method of an embodiment of the invention comprises the following steps: i. Adding nickel(ll)nitrate hexahydrate and iron(lll)nitrate nonahydrate to tungstated zirconium in a water-ethyl alcohol medium, ii. sonicating and mixing the solution obtained in step i., iii. removing alcohol and water in the solution from the medium, iv. drying the substance obtained in step iii., v. performing the calcination process.

According to this embodiment of the invention, nickel (ll)nitrate hexahydrate is added to the WOx-ZrOs base material prepared in step a. in the synthesis of Ni-Fe dopped WOx-ZrOs catalyst in a range of 5-25% by weight or preferably 7.9-22.1 % by weight of nickel metal. According to this embodiment of the invention, the iron (lll)nitrate monohydrate is added to the WOx-ZrOs base material prepared in step a. in the synthesis of Ni-Fe dopped WOx-ZrO2 catalyst in a range of 1-20% by weight or preferably 2.9-17.1% by weight of iron metal.

The amount of nickel(ll)nitrate hexahydrate added in step i. in step b. in the method of an embodiment of the invention is in the range of 3500-10000 mg or preferably in the range of 3890-9880 mg.

The amount of the iron(lll)nitrate nonahydrate added in step i. in step b. in the method of an embodiment of the invention is in the range of 1-250 mg or preferably in the range of 1.24- 210 mg.

WOx-ZrOs and metal-containing substances in the above embodiments of the invention are mixed in a water-ethyl alcohol medium by weighing nickel(ll)nitrate hexahydrate and iron(lll)nitrate nonahydrate.

According to an embodiment of the invention, the resulting solutions are sonicated in step ii. for 1 -3 hours or preferably for 2 hours. It is then stirred for 8-12 hours or preferably 10 hours.

In one embodiment of the invention, the mixture of alcohol and water in the solution is removed from the medium in the rotary evaporator in step iii. in step b. Then, in step iv., it is dried at 100-120°C or preferably 110°C for 12 hours.

In one embodiment of the invention, after the drying step, the catalyst production process is completed by calcining for 5-10 hours in an ash oven at a heating rate of 3-10°C/min at 400- 800°C or preferably 500-700°C. The resulting catalyst is finally activated under hydrogen flow in the temperature range of 600-700°C and made ready for use.

Another embodiment of the invention relates to the use of the compound having the formulation NiFe/WOxZrC as a catalyst for obtaining 2-methyl furan from the furfural compound.

Example - 1 For the synthesis of the support material (WOxZrOs), ammonia was slowly added to the zirconium oxochloride solution to form Zr(OH)4 until pH=8 at room temperature, then washed until there was no chlorine ion in the medium and checked with AgNO3 to see if there was chlorine ion in the medium. After washing, drying was applied and then Zr(OH)4 particles were obtained. With the resulting Zr(OH)4, the aqueous solution ratio of the ammonium meta tungstate to be used as a tungsten source was taken into a volumetric flask in the range of 3.2 to 36.8 and refluxed in the range of 2-12 hours. After the experiment, the solid product was filtered and calcined in the temperature ranges of 630-970°C.

Adding nickel and iron metals to the support material

In the Ni-Fe dopped WOx-ZrOs catalyst synthesis, on the WOx-ZrOs base material prepared in the previous step, nickel(ll)nitrate hexahydrate in the range of 3890-9880 mg and iron(l I l)nitrate nonahydrate in the range of 1.237-210 mg are weighed and mixed in the water-ethyl alcohol medium. The obtained solutions were sonicated for 2 hours and then stirred for 10 hours. At the end of mixing, the mixture of alcohol and water in the solution was removed from the medium in the rotary evaporator, then the remaining material was dried at 110°C for 12 hours. After the drying step, the synthesis was completed by calcining in an ash oven at 500-700°C for 5-10 hours at a heating rate of 3-10°C/min. The synthesized catalyst was finally activated under hydrogen flow in the temperature range of 600-700°C and became ready for use.

The XRD patterns of WOx-ZrOs and Ni-Fe dopped WOx-ZrOs catalyst support material are provided in Figure 1 and Figure 2, respectively. It is seen that WOx-ZrOs and Ni-Fe dopped WOx-ZrOs structures are successfully synthesized from the XRD patterns of catalysts in accordance with the literature. In Figure 3A and 3D, it is seen from the EDX spectra that Ni and Fe are included in the structure.

The scope of protection of the invention is specified in the attached claims and cannot be limited to those explained for sampling purposes in this detailed description. It is evident that a person skilled in the art may exhibit similar embodiments in light of the above-mentioned facts without drifting apart from the main theme of the invention.