NOVEL INORGANIC AND CARBONACEOUS CATALYSTS FOR PROTON TRANSFER REACTIONS

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Budarin NOVEL INORGANIC AND CARBONACEOUS

1 RENEWABLE RESOURCES & BIOREFINERIES CONFERENCE 6th-8th September, 2006 THE UNIVERSITY of YORK, York, UK V. Strelko, J. Clark, S. Tennison, V. Budarin NOVEL INORGANIC AND CARBONACEOUS CATALYSTS FOR PROTON TRANSFER REACTIONS Institute for Sorption and Problems of Endoecology, Kiev, Ukraine University of York, UK MAST Carbon, UK

2 Introduction According to K.Tanabe [Applied[ Catal.. A: General, 181 (1999) 399] ] now near 120 industrial processes from 130 ones are catalyzed by solid acids. The solid acid catalysts have many advantages over liquid Bronsted- and Levis-acid catalysts, first of all using in liquid phase processes. They are: noncorrosive and environmentally benign presenting fewer disposal problems much easier repeated use and separation from liquid products longer catalyst life can be designed to give higher activity and selectivity Our report presents the findings on novel catalysts of proton transfer reactions (solid acid catalysts) based on sulfated Zr- and Ti-oxides and modified carboneceous materials

3 Sulfated ZrO 2, TiO 2 and SnO 2 strong solid acid catalysts Synthesis: impregnation by 3-4% H 2 SO 4 or (NH 4 ) 2 SO 4, drying and calcination ( С) Calcination at С (crystallization) amorphous ZrO 2 (atmosphere wetness) These materials have already been considered as perspective low-temperature catalysts of skeletal isomerization of n-paraffins last 15 years. tetragonal modification In pioneer paper by Prof. J.Clark and coauthors (J.Catal. 193 (2000) 348) the concepts on outlook of theese catalysts application for organic synthesis reactions in liquid phase are formulated for the first time. V. Strelko, Kinetics and Catalysis, 44 (2003) 834.

4 Sulfated zirconia as an efficient catalyst for fine organic synthesis (including the solvent-less less conditions) In the last 2-3 years the increased interest has been expressed to the use of ZrO 2 / SO 4 2- as solid acid catalyst because it exhibits an excellent activity and good selectivity for a wide range of organic syntheses and transformation reactions which have a commercial value: - isomerization,, hydration, dehydration etherification and esterification processes (dibutyl- and dioctilphtalate- type plasticizers) - therapeutic active compounds and intermediates (in the field of drugs and pharmaceuticals) - Frieded-Crafts alkylation of phenols with alkenes, alkanols, ethers and alkyl halides J. Catal. 215 (2003) 57 Applied Catal.. A: General 269 (2004) 187 J. Molec. Catal. A: Chemical 237 (2005) 93 J. Molec. Catal.. A: Chemical 243 (2006) 77

5 LIQUID-PHASE ORGANIC SYNTHESIS CATALYZED BY SULFONATED ZrO 2 (solvent-less less conditions) benzodiazepines diaryl sulfoxides tetrahydropyranylation of alcohols and phenols B.M.Reddy et al., J. Molec. Catal. A: Chemical (2005) 237,

6 As a rule, sulfonated Ti- and Zr-oxides are produced in powder form which is inconvenient for handling. In Institute for Sorption and Problems of Endoecology,, National Academy of Sciences of Ukraine (Kiev), the original sol-gel methods for continuous production of spherically granulated ZrO 2 /SO 4 and TiO 2 /SO 4 acid catalysts with controlled granules sizes, porosity and surface chemistry are developed and realized in semi-plant scale.

7 SOl-GEl SYNTHESIS (main idea) - Under development of new sol-gel methods for preparation of hydrated Ti- and Zr-oxides we start from the state that precipitation is faster process then gelation. - From our point of view, slowing down of dispersed solid phase formation can be reached using the complexing agents (organic complexons) ) which have an affinity to Ti or Zr compounds in reaction systems. In other words, bringing the complexons can solve the problems of hydrogel receiving in system where in ordinary conditions precipitates could by obtained only: ZrOCl 2 + NH 4 OH ZrO 2 nh 2 O (precipitate) Zr(OR) 4 + H 2 O H + ZrO 2 nh 2 O (gel) ZrOCl 2 + NH 4 OH + [ CO(NH 2 ) 2, NH 4 Ac, (COOH) 2 ] ZrO 2 nh 2 O (gel) (complexons) - It means that in our case Ti and Zr alkoxides (traditionally used in sol-gel technologies) is excluded; ; the more accessible and convenient in handing salts (chlorides, sulfates) of Ti and Zr,, acids, alkalis and complexons are utilized instead.

OIL-DROP and AIR-DROP TECHNOLOGIES for PREPARING the SPHERICALLY GRANULATED OXIDES HYDRATED and PHOSPHATES of Ti and Zr An original sol-gel methods of synthesis developed by us allow to control

This allowed to develop two semi-pilot technologies of continuous synthesis of individual and mixed oxides hydrated and also phosphates of polyvalent metals in the shape of highly porous spherical

8 OIL-DROP and AIR-DROP TECHNOLOGIES for PREPARING the SPHERICALLY GRANULATED OXIDES HYDRATED and PHOSPHATES of Ti and Zr An original sol-gel methods of synthesis developed by us allow to control gelation time, particularly to realize gels coagulation in 3-5 seconds. This allowed to develop two semi-pilot technologies of continuous synthesis of individual and mixed oxides hydrated and also phosphates of polyvalent metals in the shape of highly porous spherical granules, namely Oil-drop and Air-drop technology (see scheme). hydrogel granula dried catalysts Oil-drop technology is based on fast injection of quickly mixed reagents in column with oil or another organic liquid (like undecane). Entering the column reactive mixture stream is divided for spherical drops (of controlled size) which is transforming into spherical hydrogel granules during few seconds at the movement through the layer of oil in column. Air-drop technology is organized in the same way, however, the drops of reactive mixture are entering the air stream (instead of oil) blowing bottom on of the column and controlling the timemovement if the hydrogel drops until they reach the flow of washing solution or water.

9 Porometric characteristics and acidity of sulfated oxides The pore size distribution of initial (line 1) and hydrothermally treated (line 2) catalysts based on Ti O 2 The curves of potentiometric titration of parent ZrO 2 as well as samples treated by H 2 SO 4 and calcinated at various temperatures

10 Based on oxidized carbons catalysts for proton transfer reactions

11 Known types of functional groups in surface layer of oxidized carbons

12 MOLECULAR STRUCTURE of CARBONS with SMALL and HIGH OXIDATION DEGREE C 95 O 4 H 22 C 97 O 8 H 22 C 102 O 18 H 22 ~0.3 ~1.2 ~2.6 Ion exchanging capacity for Na + -ions at ph=11 (Boehm), meq/g.

13 Catalytic esterification of acetic acid with buthanol (gaseous phase) in presence of oxidized carbons (H + -modification) Efficiency of the process as a function of oxidation degree (a) and temperature (b)

hundreds medical establishments as effective means of detoxifying of human organism at treatment of

16 From the beginning of 80-th years of the last century the Institute for Sorption and Problems of Endoecology (Kiev, NASU) organized semi-pilot production of these materials which were applied in hundreds medical establishments as effective means of detoxifying of human organism at treatment of plenty heavy diseases and poisonings Appeared clinical effect after enterosorption Enterosorption method

20 a - Curves of ph-potentiometric titration of synthetic carbon oxidized by nitric acid up to various degrees of oxidation (IEC): 1-1.2; 2-1.3; 3-1.8; 4-2.4; 5-2.8; meq/g; b Dependence of pk a values for carbons: 1- KAU and 3- SCN oxidized by nitric acid; 2- KAU oxidized by air. ph = pk a lg[(1-α)/α ] pk a = -lgk eq. α level neutralization of COOH groups.

21 Stronger acidity of carboxylic groups on the surface of oxidized carbon is determined by two factors:

22 Known from published papers reactions which are accelerated in presence of oxidized carbon: Esterification of acetic acid with buthanol in liquid and gaseous phase; Esterification of aliphatic acids with glycerol; Pinacolin rearrangement; Hydrolysis of ethylacetate in gaseous and liquid phase; Hydrolysis of cooking oil; Hydrolysis (inversion) of carbohydrates (saccharose,, glucose); Dehydration of methanol and isobuthanol; Reesterification of nutritive oils and fats and their mixtures. Oxidized carbons have the greater catalytic activity than the carboxyl cationites and even sulfocationites. 1) Strazhesko D.N.,Skrypnik Z.D., Strelko V.V.. In: Adsorbents, their production, properties and application, Leningrad, Nauka,, 1977, p. 105 (in Russia). 2) Tarkovskaya I.A. Oxidized carbon, Kiev, Naukova Dumka,, 1981 (in Russia). 3) Stavitskaya S.S., Davydov V.I., Strelko V.V.. Proton catalysis on oxidized carbons. Europ.. Carbon. Conf. Carbon-96, UK, v.2, p. 699.

23 Conclusions The original oil-drop and air-drop sol-gel methods for continuous production process of spherically granulated hydrated oxides and phosphates of titanium and zirconium are developed. Such hydrogels and xerogels of spherically granulated hydrated Ti- and Zr-oxides are usable for production (by sulfonation) ) of strong solid acid catalysts with controlled porosity and surface chemistry. The increase of acidity (proton mobility) of surface functional groupings with increase of the degree of their oxidation is established by potentiometric titration. It is revealed that pka value of the most acid groupings reaches 1,2-1,4. 1,4. The catalytic activity of oxidized carbons is studied in the proton transfer reactions esterification,, hydrolysis, reesterification of cooking oils, etc.; their high activity as well as stability in H + - and saline forms are shown.

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