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Summer Research Fellowship Programme of India's Science Academies

Furfural condensation by using solid base catalyst

Shivajee S. Jadhav

Department of Chemistry, Sanjay Ghodawat University, Kolhapur-416118

Lakshmi Kantam Mannepalli

Department of Chemical Engineering, Institute of Chemical Technology, Matunga, Mumbai-400019.

Abstract

The development in the catalytic area has helped the condensation of renewable resources to the value added products. In this work, three catalysts were synthesized as Mg-Al-HT, Zn-Mg-HT, and Ca- HAP by using the Co-precipitation method. 10% Zn@Mg-Al-HT synthesized by using the Mg-Al-HT with loading of 10% zinc content by wet impregnation method. The characterization of the catalysts was done using XRD analysis. The optimized catalyst was used in the condensation of the renewable reactant, furfural to 4-(-2-furyl)-3-buten-2-on (FAc), 1, 4-pentadien-3-on-1,5 di-2-furanyl (F2Ac) and 4-methylpent-3-en-2-on using acetone at 100°C with 1:10 (furfural to acetone mole ratio). The reaction conditions were optimized and the obtained reaction product was analyzed by using the GC-MS. The exact product information was obtained from GC-MS of the reaction mass and matched well with the actual reported reaction mass.

 Keywords: furfural condensation, hydrotalcite, modified hydrotalcite catalyst, XRD

Abbreviations

4-(-2-furyl)-3-buten-2-on (FAc)  
1, 4-pentadien-3-on-1,5 di-2-furanyl (F2Ac)  
X-ray diffraction XRD  

INTRODUCTION

Background

Now a day’s tremendous efforts have been devoted to the sustainable production of fuels and chemicals from renewable biomass by using the solid base catalytic reactions with increasing environmental concerns [1]. Recently, the cross aldol condensation of furfural with ketones and acids has been intensively studied by using various base catalysts in the growing field of biomass conversion [1,2]. Hydrotalcite (HT) is the one of the best mixed metal oxide catalyst like inorganic heterogeneous solid catalysts and hence it was widely used in various reactions depending upon the bacisity [3]. The condensation of aldehyde with ketones and acids is a well-known reaction of organic synthesis and it proceeds in the presence of catalysts having basic or acidic properties [4,5]. Most often basic catalysts are used for this reaction because they possess high activity in conversion of reagents and high selectivity toward the desired reaction products. The design and development of environment-friendly solid base catalysts to replace soluble bases for C–C bond formation in organic transformations widely employed in the bulk and fine chemical industries in order to achieve atomic selectivity of the desired product and reduce the salts formed as a result of neutralisation of soluble bases is of intense research activity. The classical methods for this important transformation involving the use of bases such as alkali metal hydroxides, carbonates, bicarbonates, alkoxides, barium and calcium hydroxide, magnesium and aluminium ethoxides, a rhodium complex, potassium exchanged zirconium phosphate and also organic bases such as primary, secondary and tertiary amines predominantly give dehydrated products.

Recently, the new materials with properties similar to crystalline hydrotalcite materials have widely applied in the field of catalysis. At the same time, number of reports were made on Mg-Al-HT [4], Zn(Mg)Al oxides [5] and (Pt–Bi/HT) [6] as promising materials for catalysis. In addition the Zn-Mg-HT and Zn-Mg-Al-HT materials have highly efficient in catalysis. In search of new materials with low cost processing variety of materials are now attracting their focus in researchers mind based on mixed metal oxides[2,7,8]. In order to prepare these nanocrystalline catalysts attempts will be done on controlling size, shape, crystal structure and composition of material by adopting precipitation and wet impregnation method [9]. In order to achieve high conversion and selectivity, the reaction was studied with respect to time, temperature, mole ratio of reactants, catalyst loading, zinc content and the calcination temperature.

Statement of the Problems

Present work emphasizes the fabrication of advanced nanostructure hydrotalcite materials with acceptable ability to catalysis using low cost processing is a promising alternative for large scale application of green chemistry. In this regard, we have planned to synthesize novel hydrotalcite materials particularly Mg-Al-HT, Zn-Mg-HT, 10%Zn@Mg-Al-HT@, calcium hydroxyapatite (HAP) and /or their combination. The proposed work will be developing as innovative hydrotalcite materials for catalysis with superior performance. The combination is important key towards the realization of low operational temperature with high stability and sensitivity. To reach this goal, preparation of material by simple, inexpensive chemical method will be carried out and its catalytic performance will be studied.

Objectives of the Research

The problems associated with the present work will be addressed in following steps:-

I)  The synthesis of novel hydrotalcite materials particularly Mg-Al-HT, Zn-Mg-HT, calcium hydroxyapatite (HAP) and /or their combination by co-precipitation method.

II) To synthesize the 10%Zn@Mg-Al-HT materials by wet impregnation method.

III) The materials Mg-Al-HT, Zn-Mg-HT, 10%Zn@Mg-Al-HT@, calcium hydroxyapatite (HAP) as catalyst will be characterized using structural and morphological characterization techniques such as XRD, FE-SEM, etc.

IV) To study the catalytic properties like gas selectivity, sensitivity, response and recovery time of prepared material and optimizing parameters for better sensitivity.

V) The prepared materials are used for condensation reactions.

Scope

The hydrotalcite materials have great success in the field of catalysis, photocatalysis, degradation of various dyes etc. So, we have selected the hydrotalcite materials and or their combinations for organic transformation reactions. The synthesized nanomaterials have widely used in the furfural condensation reactions.

LITERATURE REVIEW

Information

Recently, in the search of the novel, inexpensive, low-cost, high-efficiency catalyst as nanomaterials synthesis with substantial progress is the challenging task due to its unique physical and chemical properties. Hence, scientists progress towards the synthesize the hydrotalcite materials. The chemical synthesis of hydrotalcite materials gives access to large variety of compounds in the catalysis and characterized by the XRD, SEM, GC-MS. The condensation of aldehyde with ketones and acids is a well-known reaction of organic synthesis and it proceeds in the presence of catalysts having basic or acidic properties. Most often basic catalysts are used for this reaction because they possess high activity in conversion of reagents and high selectivity toward the desired reaction products. The new materials with properties similar to crystalline hydrotalcite materials have widely applied in the field of catalysis. At the same time, number of reports were made on Mg-Al-HT, Zn(Mg)Al oxides and (Pt–Bi/HT) as promising materials for catalysis. In addition the Zn-Mg-HT and Zn-Mg-Al-HT materials have highly efficient in catalysis. In search of new materials with low cost processing variety of materials are now attracting their focus in researchers mind based on mixed metal oxides, hydrotalcite nanomaterials.

Summary

In order to prepare these nanocrystalline catalysts attempts will be done on controlling size, shape, crystal structure and composition of material by adopting precipitation and wet impregnation method. In order to achieve high conversion and selectivity, the reaction was studied with respect to time, temperature, mole ratio of reactants, catalyst loading, zinc content and the calcination temperature. The development in the catalytic area has helped the condensation of renewable resources to the value added products. In this work, three catalysts were synthesized as Mg-Al-HT, Zn-Mg-HT, and Ca- HAP by using the Co-precipitation method. 10% Zn@Mg-Al-HT synthesized by using the Mg-Al-HT with loading of 10% zinc content by wet impregnation method. The characterization of the catalysts was done using XRD analysis. In particular, furfural condensation with acetone by using solid base catalyst (mole ratio1:10), was carried out. Furfural was converted into 4-(-2-furyl)-3-buten-2-on (FAc), 1, 4-pentadien-3-on-1,5 di-2-furanyl (F2Ac) and 4-methylpent-3-en-2-on respectively . The process involves no solvent addition making it overall an environmentally benign and hence a green process. The heterogenous catalyst can be reused with almost same conversion and selectivity. The reaction conditions were optimized and the obtained reaction product was analyzed by using the GC-MS. The exact product information was obtained from GC-MS of the reaction mass and matched well with the actual reported reaction mass.

METHODOLOGY

The co-precipitation method was used to prepare modified Mg–Al-hydrotalcite (Mg/Al ratio = 2.5) as follows: an aqueous solution (0.221 l) containing Mg(NO3)2 ·6H2O (0.2213 mol) (Aldrich) and Al(NO3)3 ·9H2O (0.0885 mol) (Aldrich) was added slowly to a second solution (0.221 l) containing NaOH (0.7162 mol) and Na2CO3 (0.2084 mol) in a 1 l round-bottom flask under vigorous stirring. The addition took nearly 3 h. Then the contents were heated to 338 K for 16 h. The precipitate formed was filtered off and washed with hot distilled water until the pH of the filtrate was 7. The precipitate was dried in an oven at 353 K for 15 h.

The 10%Zn@ Mg-Al-HT was prepared by using weight impregnation method. Take a 3 gm of Mg–Al -hydrotalcite powder taken in 50 ml distilled water and add to it slowly 50 ml the solution of zinc nitrate hexahydrate (1.365gm). The mixture was stirred well and evaporates the solution to dry at constant heating temperature to obtain the 10%Zn@ Mg-Al-HT.

The Zn-Mg-hydrotalcite (Mg/Zn ratio=2:1) was prepared by using the stoichiometric amount of zinc nitrate (0.05 mol), magnesium nitrate (0.1 mol) was added to second solution containing NaOH and Na2CO3 in a round-bottom flask under vigorous stirring. Then the contents were heated to 800C for 15 h. The precipitate formed was filtered off and washed with hot distilled water until the pH of the filtrate was 7. The precipitate was dried in an oven at 353 K for 15 h. After that the catalyst formed is crushed in a mortar pastel and kept for calcination at 550°C for 3 hours.

Concepts

The furfural condensation was carried out by using various types of solid base catalyst. The catalytic reactions of hydrotalcite nanomaterils with furfural and acetone was carried out in autoclave experiments.

Methods

The 10%Zn@ Mg-Al-HT was prepared by using weight impregnation method. Take a 3 gm of Mg–Al -hydrotalcite powder taken in 50 ml distilled water and add to it slowly 50 ml the solution of zinc nitrate hexahydrate (1.365gm). The mixture was stirred well and evaporates the solution to dry at constant heating temperature to obtain the 10%Zn@ Mg-Al-HT.

The Zn-Mg-hydrotalcite (Mg/Zn ratio=2:1) was prepared by using the stoichiometric amount of zinc nitrate (0.05 mol), magnesium nitrate (0.1 mol) was added to second solution containing NaOH and Na2CO3 in a round-bottom flask under vigorous stirring. Then the contents were heated to 800C for 15 h. The precipitate formed was filtered off and washed with hot distilled water until the pH of the filtrate was 7. The precipitate was dried in an oven at 353 K for 15 h. After that the catalyst formed is crushed in a mortar pastel and kept for calcination at 550°C for 3 hours.

For autoclave experiments, 2 g of catalyst was mixed together with the reaction mixture of 19.25 g acetone and 3.25 g of furfural (acetone/furfural molar ratio 10/1) composition and loaded into the autoclave. After initiation of the heating the desired temperature was achieved in ∼60 min, and the autoclave was kept at T = 100 ◦C for additional 6h. The reaction mass was analyzed using GC-MS and products were confirmed.

In particular, furfural condensation with acetone by using solid base catalyst (mole ratio1:10), was carried out. Furfural was converted into 4-(-2-furyl)-3-buten-2-on (FAc), 1, 4-pentadien-3-on-1,5 di-2-furanyl (F2Ac) and 4-methylpent-3-en-2-on respectively . The process involves no solvent addition making it overall an environmentally benign and hence a green process. The heterogenous catalyst can be reused with almost same conversion and selectivity.

RESULTS AND DISCUSSION

XRD

The crystal structure quality, structural parameters and nature of sample structure, crystalinity of the catalyst were probed by the X-ray diffraction of the make Bruker AXS, D8 Discover USA with CuK radiations in the range from 10 to 70o. The Fig. 1 provides the XRD patterns of Zn-Mg-HT, Fig. 2 provides the XRD patterns of 10%Zn@Mg-Al-HT, and Fig. 3 provides Ca-HAP Catalyst. Abroad sharp peak with low intensity was detected in the range of 20-650 in diffractograms of all catalyst. This signal generally depicts in large amount of crystallite structure. These diffraction peaks denotes presence of larger crystallites. The experimentally obtained values are good agreement with standard values confirming the formation of crystal structure and good agreement with literature [5, 10].

The Bragg angle and the values of the interplanar spacing, d, obtained were subsequently matched with the standard values for Ca, and other related phases of Ca-HAP catalyst. The crystal size of the as received powder and sintered bodies has been also determined using XRD technique. The Full Width Half Maximum (FWHM) for each peak has been detected at specific 2θ degree and evaluated using known Scherer formula.

Picture3_1.png
    XRD patterns of the catalyst Zn-Mg-HT
    Picture2_1.png
      XRD patterns of the catalyst 10%Zn@Mg-Al-HT
      Picture1_1.png
        XRD patterns of Ca-HAP 

        The condensation reaction of furfural was initially carried out with multiple catalysts from which it was screened down to Zn-Mg-HT catalyst. Fig. 4 provides the information of reaction pathways of aldol condensation of furfural with acetone. The condensation was carried with Zn-Mg-HT as a solid base catalyst for about 6 hours at 100°C. The furfural to acetone molar ratio was kept to about 1:10 which was equal to the theoretical ratio. The conversion of furfural into 4-(-2-furyl)-3-buten-2-on (FAc), 1,4-entadien-3-on-1,5 di-2-furanyl (F2Ac) and 4-methylpent-3-en-2-on etc products was confirmed by using GC-MS and as shown in figure 5. The method of synthesis of catalyst and their applications in the field of catalytic reaction was simple and inexpensive.  

        Picture5_1.png
          Aldol condensation between furfural and acetone over basic catalysts.
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            GC-MS Spectra of Aldol condensation reaction of furfural with acetone.

            Purpose

            The developed method is simple, rapid, efficient for condensation reaction and the catalyst used was reusable. The results obtained in this experiment were excellent and motivational to the researchers. The developed method was useful to prepare novel combinations of hydrotalcite nanomaterials. The autoclave experiment of acetone condensation with furfural was carried out using solid base catalyst. So, In future, we have planned furfural condensation, and oxidation reactions using different types of solid base catalysts. The industrially important catalyst synthesis and their catalytic investigation is particularly important in the field of green chemistry.

            CONCLUSION

            In conclusion, in this work, three catalysts were synthesized as Mg-Al-HT, Zn-Mg-HT, and Ca- HAP by using the co-precipitation method. The 10% Zn@Mg-Al-HT synthesized by using the Mg-Al-HT with loading of 10% zinc content by wet impregnation method. The condensation reaction of furfural was initially carried out with multiple catalysts from which Zn-Mg-HT catalyst was found be good. . We have carried out the condensation reactions by using solid base catalyst to convert furfural into 4-(-2-furyl)-3-buten-2-on (FAc), 1,4-pentadien-3-on-1,5 di-2-furanyl (F2Ac) and 4-methylpent-3-en-2-on etc products. In this investigation, industrially valuable chemicals have been produced which are obtained from a bio-source making it an environmentally cordial process. In future, we have planned furfural condensation, and oxidation reactions using different types of solid base catalysts. The industrially important catalyst synthesis and their catalytic investigation are particularly important in the field of green chemistry.

            REFERENCES

            [1] Oleg Kikhtyanina, Vendula Kelbichováa, Dana Vitvarováb, Martin Kubub D K 2014 Aldol condensation of furfural and acetone on zeolites Catal. today 227 154–62

            [2] Liang G, Wang A, Zhao X, Lei N and Zhang T 2016 levulinic acid and furfural in aqueous-phase over Green Chem. 18 3430–8

            [3] R. L. Frost•, W. Martens, Z. Ding J T K and Centre 2003 Differential scanning calorimetry and high-resolution thermogravimetric analysis of synthesized hydrotalcites of Mg and Zn R. J. ofThermal Anal. Calorim. 71 429–38

            [4] Choudary B M, Kantam M L, Rao K K, Figueras F and Einstein A A 1999 Henry reactions catalysed by modified Mg – Al hydrotalcite : an efficient reusable solid base for selective synthesis of Green Chem. 187–90

            [5] Smola L, Frolich K, Koc J, Kikhtyanin O and Libor C 2017 Surface Properties of Hydrotalcite-Based Zn ( Mg ) Al Oxides and Their Catalytic Activity in Aldol Condensation of Furfural with Acetone

            [6] Xue W, Wang Z, Liang Y, Xu H and Liu L 2018 Promoting Role of Bismuth on Hydrotalcite- Supported Platinum Catalysts in Aqueous Phase Oxidation of Glycerol to Dihydroxyacetone 10–6

            [7] Chye S, Loo J, Eva Æ Y, Ho S, Yin Æ F and Boey C 2008 Synthesis and hydrothermal treatment of nanostructured hydroxyapatite of controllable sizes 1389–97

            [8] Hernández W Y, Aliç F and Voort P Van Der 2017 Tuning the acidic–basic properties by Zn-substitution in Mg–Al hydrotalcites as optimal catalysts for the aldol condensation reaction J. Mater. Sci. 52 628–42

            [9] Zhou R, Cao Y, Yan S and Fan K 2002 Rare earth ( Y , La , Ce ) -promoted V-HMS mesoporous catalysts for oxidative dehydrogenation of propane 236 103–11

            [10] Khalil K A 2012 A New-Developed Nanostructured Mg / HAp Nanocomposite by High Frequency Induction Heat Sintering Process 7 10698–710

            ACKNOWLEDGEMENTS

            I am very much thankful to Summer Academaies for awarding the IASC-INSA-NASI Summer research fellowship-2019. I am also thanks to Prof. M. Lakshmi Kantam, ICT, Mumbai for very kind coperation and valuable guidance.

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