SK Hydrodesulfurization (HDS) Pretreatment Technology for Ultralow Sulfur Diesel (ULSD) Production

SK Corporation of Korea has developed a unique process, SK hydrodesulfurization (HDS) pretreatment technology, to produce ultralow sulfur diesel (ULSD) with pretreatment of the middle-distillate-range petroleum fractions. This technology has been successfully demonstrated through a 1000 barrel/day (B/D) demonstration plant, which has been running since May 2002. This technology is based on the adsorptive removal of a small amount of nitrogen-based natural polar compounds (NPC). Dramatic improvement in deep HDS efficiency is observed with the removal of NPC from the feedstock.SK HDS pretreatment process consists of multiple adsorbers, two stripping columns for desorbent recovery, associated pumps, and overhead system. Middle distillate feed is pretreated prior to HDS process in the adsorbent vessels followed by stripping to remove a small amount of desorbent. The pretreated is then sent to the downstream HDS unit for sulfur removal. The rejected stream with high nitrogen content, about 2vol%, can be either used as a blending stock for heavy petroleum products or processed in other refining units.This paper describes the fundamental principle of the process, discusses the case study results with various feedstocks and operation conditions in pilot plant and demonstration plant, and provides economic assessment data.     

MCM-41分子筛负载钼钴系催化剂的噻吩HDS研究

通过氧吸附量、噻吩吸附热及反应速率常数的测定，研究了MoO3/MCM-41、MoO3-CoO(NiO)/MCM-41系列催化剂，发现，对于MoO3/MCM-41催化剂，当MoO3的质量分数（以MCM－41为底数，即MCM－41＝1g时，MoO3含量为0．15g，下同）从15％增加到20％时，其噻吩的加氢硫（HDS）活性增大，至25％时活性下降，所对应的氧吸附量（mL/g催化剂）也是先增大后减少，并且两者有很好的线性对应关系，而且噻吩吸附热则基本保持不变，采用不同的MoO3-CoO(NiO)浸渍顺序制备的MoO3-CoO(NiO)/MCM-41催化剂中，先浸渍CoO(NiO）再浸渍MoO3的催化剂，其噻吩HDS活性明显优于对其它浸渍顺序制备的催化剂，同时催化剂的氧吸附量和噻吩吸附热也最大。     

Alkynyl- and Alkenyl(phenyl)iodonium Compounds. New Synthetic Methods (86)

Compounds with highly coordinated, polyvalent main-group elements represent an interesting alternative to the many well-known transition-metal complexes. Among the oldest and best known stable examples of such organic molecules are the iodine(III) compounds. Diaryliodonium species, Ar₂IX, for example, have been known for over a hundred years and play an important role in lithography. Likewise, acetylenes and olefins are among the oldest, most important, and most valuable compounds in chemistry. Besides simple hydrocarbon alkenes and alkynes, numerous functionalized derivatives are also known and widely employed in organic chemistry. Despite the ubiquity and prominance of both I^III species and olefins and acetylenes, the combination of these two types of functional groups in a single molecular unit, namely compounds with polyvalent iodine and at least one alkyne or olefin residue, was unknown until recently. The successful preparations of simple alkynyl- and alkenyl-(phenyl)iodonium species during the 1980s has resulted in a renaissance in both acetylene and I^III chemistry. These alkynyliodonium compounds readily undergo nucleophilic substitution on the alkyne moiety (S_N-A reactions) which are difficult with other substrates. The application of a wide variety of nucleophiles in this reaction resulted in diverse functionalized alkynes including previously unknown acetylenic carboxylates, sulfonates, and phosphates. These are excellent substrates for cycloaddition reactions as well as numerous other interesting chemical transformations.     

Koordination von Rhodium(III), Iridium(III) und Kupfer(II) mit dem potentiell vierzähnigen Akzeptorliganden Bis(1‐methylimidazol‐2‐yl)glyoxal (big)

Coordination of Rhodium(III), Iridium(III), and Copper(II) with the Potentially Tetradentate Acceptor Ligand Bis(1‐methylimidazol‐2‐yl)glyoxal (big) Bis(1‐methylimidazol‐2‐yl)glyoxal (big) which has hitherto not been used in coordination chemistry crystallizes to form two perpendicular 1‐methylimidazol‐2‐yl‐carbonyl molecular halves. Out of the various possibilities for mono‐ and bis‐chelate coordination the N,N′‐alternative with a seven‐membered chelate ring is realized in [Cp*Cl(big)Rh](PF₆) as evident from crystal structure analysis. The iridium analogue reacts under hydration of big and elimination of HCl to form a complex cation [Cp*(bigOH)Ir]⁺ which dimerizes in the crystal through hydrogen bonding and contains one five‐ and one six‐membered chelate ring involving the alcoholate‐O. Cu(ClO₄)₂ and the ligand big yield a complex ion [Cu(big)₂]²⁺ with an ESR spectrum that suggests the coordination of the central metal by four N atoms in an approximately planar setting.     

Crystal Structure of Mixed Crystals of the Tetra(n-butyl)ammonium Salts of cis-Tetrafluorophthalocyaninato(2−)tantalate(V) and cis-Trifluorophthalocyaninato(2−)tantalate(IV)

cis-Trichlorophthalocyaninato(2?)tantalate(V) reacts with excess tetra(n-butyl)ammonium fluoride trihydrate yielding mixed crystals of the tetra(n-butyl)ammonium salts of cis-tetrafluorophthalocyaninato(2?)tantalate(V) and cis-trifluorophthalocyaninato(2?)tantalate(IV) in the ratio five to four. These crystallize in the monoclinic space group P2₁/ n with cell parameters: a = 13.368(2) Å, b = 13.787(2) Å, c = 23.069(3) Å, β = 93.35(1)°, Z = 4. Ta^v is octacoordinated with four F atoms and four N_iso atoms in an antiprismatic cis-arrangement. The Ta^v-F distance varies from 1.919(7) to 1.966(4) Å. Ta^IV is heptacoordinated with three F atoms in a cis-arrangement. The Ta^IV-F distance varies from 1.74(1) to 1.966(4) Å. The Ta atom is located out of the centre of the N₄ plane towards the F atoms by 1.234(3) Å. The Ta–N distances range from 2.261(6) to 2.310(6) Å.     

Aluminum(I) and Gallium(I) Compounds: Syntheses,Structures, and Reactions

By the end of the last century there were already the first indications of the possible existence of Al¹ halides. However, it was only through the pioneering works of W. Klemm, who would have celebrated his 100th birthday on January 6, 1996, that detailed spectroscopic investigations became possible. Since the end of the 1970s the reactivity of AlX and GaX species in solid noble gases has been confirmed by numerous examples. In recent years formally monovalent Al and Ga species have been successfully synthesized on a preparative scale. In addition to the first halides, organometallic compounds with metal–metal bonds have been isolated and investigated with regard to their chemical properties. The fundamental importance of such species has been documented in this journal among others in the form of two highlight articles in which experimental and theoretical aspects have been examined with examples, and parallels and differences with respect to boron chemistry have been illustrated. This review is intended to give an account of the chronological development of this research area over the last few years, but an attempt is also made to categorize the experimental results achieved not only with respect to structure, thermodynamics, and reactivity, but also with the aid of quantum chemical calculations and by comparative considerations.     

A Simple Preparative Route to Bis(imido)uranium(VI) Complexes by the Direct Reductions of Diazenes and Azides

In clean, one-pot procedures , the uranium complex 1 reductively cleaves azides and azo compounds to generate bis(imido) derivatives [Eq. (a)]. This unusual reaction has not been observed previously in either the actinide series or with a metallocene complex.     

Synthesis and Cytotoxicity of 3-(Hetarylthio)-1-propynyl(trimethyl)silanes

We have developed a two-step method for synthesis of 3-(hetarylthio)-1-propynyl(trimethyl)silanes from thiols in a phase-transfer catalysis system HCCCH₂Br-solid K₂CO₃-18-crown-6-toluene followed by reaction with n-BuLi-Me₃SiCl in ether or THF. We have observed that 3-[1,3-bis(trimethylsilyl)-2-propynyl]thioindole displays high cytotoxicity in HT-1080 and MG-22A tumor cell lines.