Colin J. Schaverien

Hydrodeoxygenation of pyrolysis oil fractions: process understanding and quality assessment through co-processing in refinery units

Hydrodeoxygenation (HDO) of pyrolysis oil fractions was studied to better understand the HDO of whole pyrolysis oil and to assess the possibility to use individual upgrading routes for these fractions. By mixing pyrolysis oil and water in a 2:1 weight ratio, two fractions were obtained: an oil fraction (OFWA) containing 32 wt% of the organics from the whole oil and an aqueous fraction water addition (AFWA) with the remaining organics. These fractions (and also the whole pyrolysis oil as the reference) were treated under HDO conditions at different temperatures (220, 270 and 310 °C), a constant total pressure of 190 bar, and using 5 wt% Ru/C catalyst. An oil product phase was obtained from all the feedstocks; even from AFWA, 29 wt% oil yield was obtained. Quality parameters (such as coking tendency and H/C) for the resulting HDO oils differed considerably, with the quality of the oil from AFWA being the highest. These HDO oils were evaluated by co-processing with an excess of fossil feeds in catalytic cracking and hydrodesulfurisation (HDS) lab-scale units. All co-processing experiments were successfully conducted without operational problems. Despite the quality differences of the (pure) HDO oils, the product yields upon catalytic cracking of their blends with Long Residue were similar. During co-processing of HDO oils and straight run gas oil in a HDS unit, competition between HDS and HDO reactions was observed without permanent catalyst deactivation. The resulting molecular weight distribution of the co-processed HDO/fossil oil was similar to when hydrotreating only fossil oil and independent of the origin of the HDO oil.

Coupling fatty acids by ketonic decarboxylation using solid catalysts for the direct production of diesel, lubricants, and chemicals.

There is an increasing demand in our society for sustainable development. Along this line, efforts are being made to establish processes that transform different biomass and biomass-derived products into liquid fuels and chemicals. Biodiesel, that is, fatty acid methyl esters, together with ethanol is the largest fuel product obtained from renewable resources. In many countries, it is blended with petroleum diesel and used in unmodified diesel engines. With the aim to expand the scope of application of vegetable oil derived renewables, alternative products and processes need to be developed. For instance, it is possible to transform vegetable oil into a paraffinic diesel by direct hydrotreatment. An interesting reaction to transform carboxylic acids into symmetrical ketones is their coupling or the ketonic decarboxylation. In this reaction, two carboxylic acids are condensed, and a symmetrical ketone is formed with 2n 1 carbon atoms, together with one molecule of water and one molecule of CO2 (Scheme 1). When the reaction is carried out with stearic acid (C18) to obtain stearone, the atom economy, that is, how much mass of the reactants ends up in the product, is as high as 89 %. So, this transformation can be considered to be a sustainable and green process if a simple, non-polluting catalyst and an efficient chemical process are employed. At present, the products obtained from the condensation of fatty acids, also called fatty ketones, find interesting applications in areas such as ink manufacturing, dishwashing detergents, or in personal care products. Furthermore, fatty ketones or their derivatives can also make excellent premium diesel and lubricants. In the condensation reaction, 75 % of the oxygen of carboxylic acids is eliminated and the bulk properties of the products such as hygroscopicity are considerably modified as compared to the starting acid. Nevertheless, it should be possible through a cascade-type reaction to perform hydrogenation of the ketone followed by elimination of water and further hydrogenation to remove all the oxygen from the molecule to yield an alkane that could be interesting as a diesel or biolubricant, depending on the chain length, that is, depending on the number of carbon atoms in the original acid (Scheme 1). To this end, process intensification could be achieved by designing a multifunctional catalyst that is able to promote the condensation–hydrogenation–dehydration–hydrogenation sequence in a single reactor. To design the multifunctional catalyst, we first studied the ketonic decarboxylation of carboxylic acids. Basic magnesium oxide was selected as an environmentally friendly solid catalyst to carry out this reaction in a fixed-bed continuous reactor. With lauric acid (C12H24O2), complete conversion was achieved in less than one hour of contact time at 400 8C (Table 1). At 95 % conversion, the desired ketone (C11H23COC11H23, laurone) was obtained with excellent selectivity (97 %; Table 1, entry 5). Other potential catalysts for acid condensation are manganese oxide or Fe-Al-Si-Ti mixed oxide. Scheme 1. Formation of triocsane from two molecules of lauric acid by ACHTUNGTRENNUNGketonic decarboxylation with subsequent hydrogenation of the carbonyl group, the elimination of water, and hydrogenation of the olefin.

A new ligand environment in organolanthanoid chemistry: sterically hindered, chelating diolato ligands and the X-ray structure of [La{CH(SiMe3)2}{1,1′-(2-OC6H2But2-3,5)2}(thf)3](thf = tetrahydrofuran)

[La{CH(SiMe3)2}3]1 reacts with 1 equiv. of 3,3′,5,5′-tetra-tert-butylbiphenyl-2,2′-diol 2 to afford the monomeric chelate [La{CH(SiMe3)2}{1,1′-(2-OC6H2But2-3,5)2}]4, whose mono-5, and crystallographically characterised tris-thf adducts 6 have been synthesized; its reaction with 3,3′-bis(triphenylsilyl)-1,1′-binaphthyl-2,2′-diol 3c affords [La{CH(SiMe3)2}{1,1′-(2-OC10H5SiPh3-3)2}(OEt2)]7.

Monocyclopentadienyl Yttrium Chemistry: Incorporation of Alkoxides as Supporting Ligands and Synthesis of [Y(C5Me5)(OC6H3But2)(μ-H)]2

Reaction of the crystallographically characterised [Y(C5Me5)(OC6H3But2)2]2 with LiCH(SiMe3)2 affords the mixed alkyl–alkoxide species [Y(C5Me5){CH(SiMe3)2}(OC6H3But2)]3 which, on subsequent hydrogenation, gives the hydride bridged dimer [{Y(C5Me5)(OC6H3But2)(µ-H)}2]4; 89Y NMR spectra of these, and related complexes, allows C5Me5, OC6H3But2 and CH(SiMe3)2 group contributions to be determined.

Phosphorus-bridged metallocenes: New homogeneous catalysts for the polymerization of propene

Abstract The synthesis of a new class of metallocenes for the syndiospecific, aspecific and isospecific polymerization of propene is reported. This has been achieved by the incorporation of a phosphorus linking the cyclopentadienyl-type rings. The catalyst precursors, syndiospecific PhP(fluorenyl–Cp)ZrCl2 (2), aspecific PhP(fluorenyl)2ZrCl2 (4), and isospecific PhP(indenyl)2ZrCl2 (5), RP(2-Me,4-Ph-indenyl)2ZrCl2 (R=Ph (6); R= i Pr (7)) were prepared. Compound 2, after activation by methylaluminoxane (MAO), in LIPP at 67°C affords syndiotactic polypropene (s-PP) with an activity of 155 kg s-PP/g Zr·h. The physical properties of the s-PP (stereoregularity and molecular weight) are similar to that of conventional carbon-bridged systems. Ab initio calculations on model compounds assisted in rationalizing the high syndiospecificity of 2 in contrast to the much poorer stereoregularity of closely related Me2Si(fluorenyl–Cp)ZrCl2. Aspecific metallocene 4, after activation with MAO, affords high molecular weight atactic-PP, albeit with a low activity. Metallocenes 6 and 7, activated by MAO, afford isotactic polypropene (i-PP) with extremely high stereoregularity (>98% mmmm pentads), melting points 156–160°C and molecular weights tunable in the range 250,000–1,100,000. Activities of up to 580 kg i-PP/g Zr·h for 6/MAO (LIPP, 67°C, 37 000 equiv. MAO) and 1265 kg i-PP/g Zr·h for 7/MAO (LIPP, 50°C, 37 000 equiv. MAO) have been obtained.

Reaction of cationic cyclobutadineruthenium complexes with hydride anion donors; evidence for the formation of η4(5e) butadienyl species and fragmentation of the cyclobutadiene ring: crystal structure of [RuC(Ph)–η3-{C(Ph)·CH(Ph)·CH(Ph)}-(η-C5H5)] and [Ru2(µ-CO){µ-(Z)-C(Ph)CH(Ph)}(CO)2(η4-C4Ph4)(η-C5H5)]

Reaction of ·[Ru(NCMe)(η4-C4Ph4)(η-C5H5)][BF4] with K[BHBus3] affords the η4(5e) butadienyl complex [RuC(Ph)-η3-{C(Ph)·CH(Ph)·CH(Ph)}-(η-C5H5)], whereas a similar reaction with [Ru(CO)(η4-C4Ph4)(η-C5H5)][BF4] affords [RuC(Ph)-η3-{C(Ph)·CH(Ph)·CH(Ph)CHO}-(η-C5H5)] and the µ-vinyl complex [Ru2(µ-CO){µ-(Z)-C(Ph)CH(Ph)}(CO)2(η4-C4Ph4)(η-C5H5)].

Alkoxides as ancillary ligands in organolanthanide chemistry: Synthesis, reactivity, α-olefin and diene polymerization by [Y(C5Me5)(OC6Ht3Bu2)(μ-H)]2

Abstract Terminal olefins H 2 CCHR (R=H, Me, n -Bu) react regiospecifically and irreversibly with μ-H dimer [Y(C 5 Me 5 )(OAr)(μ-H)] 2 ( 1 ) to give the μ- n -alkyl species trans -[Y(C 5 Me 5 )(OAr)] 2 (μ-H)(μ-CH 2 CH 2 R) (R=H ( 2 ), Me ( 3 ), n -Bu ( 4 )) respectively. Reaction of[Y(C 5 Me 5 )(OAr)(μ-D)] 2 ( 4 -D) (prepared from (C 5 Me 5 )Y(OAr)CH(SiMe 3 ) 2 and D 2 ) with propene yields selectively only trans -[Y(C 5 Me 5 )(OAr)] 2 (μ-D)(μ-CH 2 CHDMe) ( 4 -D), confirming the non-reversibility of olefin insertion. Compounds 1–4 polymerize ethene and are single-component catalysts for the polymerization of α-olefins and non-conjugated dienes. Dissolution of 1 in neat 1-hexene (to give 4 in situ) results in slow polymerization to yield poly(1-hexene) with M w =15700, M w / M n =1.67. 1 cyclopolymerizes neat 1,5-hexadiene to poly(methylene-1,3-cyclopentane), rather than cyclization to methylenecyclopentane.

Monocyclopentadienyl lanthanide chemistry: towards the limits of steric unsaturation

The synthesis and single-crystal X-ray structure determinations of salt- and solvent-free La(η5-C5Me5)[CH(SiMe3)2]2, and of its THF precursor, are described. These complexes contain unusual agostic SiMe bonds that facilitate stabilization of the unsaturated lanthanum centre. The first neutral “mixed” dialkyl organolanthanide complex, Lu(η5-C5Me5)(CH2SiMe3)[CH(SiMe3)2](THF), has been prepared.

Reactions of co-ordinated ligands. Part 31. The synthesis, structure, and protonation of the octamethyloctatrienediylidenedimolybdenum complex [Mo2(µ-C8Me8)(η-C5H5)2], evidence for three-centre carbon–hydrogen–molybdenum interactions

Reaction of [Mo(NCMe)(MeC2Me)2(η-C5H5)][BF4] with Na[Fe(CO)2(η5-C5H5)] in tetrahydrofuran affords [Fe2(CO)4(η-C5H5)2] and the octamethyloctatrienediylidenedimolybdenum complex [Mo2(µ-C8Me8)(η-C5H5)2](1) identified by X-ray diffraction studies. Complex (1) crystallizes in the triclinic space group P, with a= 8.449(1), b= 10.114(2), c= 14.872(3)A, α= 86.66(2), β= 80.88(1), γ= 63.78(1), and Z= 2. The structure was refined to R= 0.020 and R′= 0.025. The molecular structure of complex (1) shows non-crystallographic Cs symmetry, and there is a formal MoMo double bond [MoMo 2.595(1)A]. The C8 carbon chain binds to the dimolybdenum unit in an σ, η3, η2, η3, σ fashion such that it forms σ bonds to one molybdenum atom of mean length 2.092(2)A, each molybdenum atom carrying an η5-cyclopentadienyl group. Extended-Huckel molecular orbital calculations on complex (1) indicate an accumulation of electron density on the carbon atoms of the C8 chain, and in agreement with this finding protonation with HBF4·OEt2 or CF3CO2H affords purple crystals of [Mo2(µ-C8Me8)(µMo,c-H)(η-C5H5)2]BF4(2) and [Mo2(µ-C8Me8)(µMo,c-H)(η-C5H5)2][(CF3CO2)2H](3). The 1H n.m.r. spectra of these cations showed a high-field signal due to the proton derived from the acid indicating the presence of a CHMo system. This was confirmed by an X-ray crystallographic study on complex (3), which crystallizes in the monoclinic space group P21/c, with a= 10.648(2), b= 15.119(4), c= 19.655(6)A, β= 105.30(2)°, and Z= 4; the structure was refined to R= 0.029 and R′= 0.034. The crystal structure of complex (3) contains isolated [Mo2(µ-C8Me8)(µMo,c-H)(η-C5H5)2]+ cations and [(CF3CO2)2H]– anions. The cation non-hydrogen atom geometry is closely similar to that of complex (1), with the exception that one of the terminal Mo–C σ bonds is markedly extended [to 2.196(5)A]. This bond is bridged by a hydrogen atom which shows Mo–H and C–H distances of 1.88(8) and 0.89(8)A, and an Mo–H–C angle 99(5)°. The complex anion contains two CF3CO2 units linked by a strong, short hydrogen bond [O ⋯ O 2.429(8), O(311)–H(42) 1.35(7), and O(412)–H(42) 1.08(7)A]. Examination of the variable-temperature (192–295 K)13C n.m.r. spectra of the cation [Mo2(µ-C8Me8)(µMo,c-H)(η-C5H5)2]+ suggests that in solution the bridging proton undergoes site exchange such that it spends some time attached to the terminal carbon atom (Cα) of the C8 chain, and the remainder attached to one of the olefinic carbon atoms (Cδ), in both cases bridging from these to the molybdenum atom.

Reactivity of [{Y(C5Me5)(OC6H3But2)(µ-H)}2] with terminal alkene and alkynes: a model for the first insertion step in alkene polymerization

Terminal alkenes H2CCHR (R = H, Me, Bun) react with [{Y(C5Me5)(OAr)(µ-H)}2]1 to give the µ-n-alkyl species trans-[{Y(C5Me5)(OAr)}2(µ-H)(µ-CH2 CH2R)](R = H 2, Me 3, Bun4), respectively; HCCSiMe3 reacts to give [{Y(C5Me5)(OAr)}2(µ-H)(µ-CCSiMe3)]5.