3.2.3. Hydroformylation 2467 3.2.4. Dimerization 2468 3.2.5. Oxidative Cleavage and Ozonolysis 2469 3.2.6. Metathesis 2470 4. Terpenes 2472 4.1. Pinene 2472 4.1.1. Isomerization: R-Pinene 2472 4.1.2. Epoxidation of R-Pinene 2475 4.1.3. Isomerization of R-Pinene Oxide 2477 4.1.4. Hydration of R-Pinene: R-Terpineol 2478 4.1.5. Dehydroisomerization 2479 4.2. Limonene 2480 4.2.1. Isomerization 2480 4.2.2. Epoxidation: Limonene Oxide 2480 4.2.3. Isomerization of Limonene Oxide 2481 4.2.4. Dehydroisomerization of Limonene and Terpenes To Produce Cymene 2481

Chemical Routes for the Transformation of Biomass into Chemicals

Converting carbohydrates to bulk chemicals and fine chemicals over heterogeneous catalysts

Within the present contribution we highlight the feasibility of standard refinery units for the production of biofuels from different biomass-derived feedstock. The energy densification of biomass, as well as it’s logistics and incorporation within the refinery supply chain is thoroughly discussed. Likewise, special attention is focused on the catalytic cracking and hydrotreating of triglyceride-rich biomass feedstock, which is probably the most suitable one for co-processing in conventional refinery conversion units. However, the opportunities of other highly oxygenated feedstocks such as pyrolysis oils and sugars are also discussed. Conversion of different feedstocks into conventional liquid fuels by coupling of aqueous phase reforming (APR) with catalytic systems typical of standard petroleum refineries is also evaluated. Thus, here we review the chemistry, catalysis and challenges involved in the production of biofuels from biomass in conventional refineries.

Biomass as renewable feedstock in standard refinery units. Feasibility, opportunities and challenges

Two procedures are discussed for the direct variational optimization of localized molecular orbitals which are expanded in local subsets of the molecular basis set. It is shown that a Newton-Raphson approach is more efficient than an iterative diagonalization scheme. The effect of the basis-set truncation on the quality ofab-initio SCF results is investigated for Be, Li2, HF, H2O, NH3, CH4 and C2H6.

On the use of local basis sets for localized molecular orbitals

We reexamine the open shell restricted Hartree-Fock theory and develop Fock-like operators that are quite general and easy to implement on a computer. We present a table of ‘vector coupling coefficients’ that define this operator for most of the cases that commonly arise. We compare the form of this operator with that suggested by others, and discuss the orbitals obtained by this procedure with respect to the generalised Brillouin's theorem, and the orbital energies with respect to Koopmans' approximation.

A generalized restricted open-shell Fock operator

Maximum and minimum overlap, localized, and hybrid orbitals for atoms and molecules by means of orthonormality‐constrained variation

The g tensors and hyperfine splitting (hfs) tensors of simple organic radicals in their triplet states have been calculated by using an all valence electron SCF MO method with a first order perturbation treatment. The molecular orbital spin density is partitioned into the σ- and π-electron spin delocalization (SD) terms and the rest terms of spin polarization (SP) which arise from the CI effect. The g tensors for CH2 and several other carbenes which have triplet ground states and for formaldehyde in its nπ* and nσ* excited triplet states are evaluated. The calculated α-proton hfs constants of CH2 contributing from the π orbital well compare with the observed hfs constants of the triplet naphthalene and the doublet malonic acid radical. The anisotropic carbon-13 hfs constants of CH2 are determined almost completely by the SD contribution and their absolute values are in good accord with those observed for CD2. Contribution of the SP terms to the isotropic hfs constant is found to be fairly large. Predictio...

Calculations of g Tensors and Hyperfine Splitting Tensors for Molecules in Their Triplet States

A general method is described which unifies a set of eigenvalue equations into one eigenvalue problem. During the formulation of this method, the arbitrariness involved in the general SCF theory is fully realized in terms of numerical parameters concerning the occupied ‖ i≳ and ‖ j≳ and virtual ‖u≳ and ‖υ≳ orbitals. The parameters are λji(=1−λij) which are necessary for constraining orthonormality among the occupied orbitals; avi(≠0) and bji(≠0, j≠i) for converting the magnitude and the direction of gradient vectors on the energy surface; and quite arbitrary matrix elements Rii and Ruv for the SCF operator. The appropriate setting of these parameters is discussed from the practical computational point of view.

Describing and removing the arbitrariness in the construction of general SCF coupling operators

The orthogonality between sets of basis vectors, referred below to as pair‐orthogonality, is examined from a variational point of view. Both how to constitute pair‐orthogonal vectors and how to retain the pair‐orthogonality conditions in the course of variation are presented. The relation of the vectors to canonically orthonormalized Lowdin vectors is noted.

Tetsuo Morikawa

Papers

Maximum and minimum overlap, localized, and hybrid orbitals for atoms and molecules by means of orthonormality‐constrained variation

Calculations of g Tensors and Hyperfine Splitting Tensors for Molecules in Their Triplet States

Describing and removing the arbitrariness in the construction of general SCF coupling operators

Method of the orthonormality‐constrained variation: A pair of basis sets and the pair‐orthogonality

Unitary variational method for atoms and molecules