Ni/ZSM-5 Catalysts for Light Olefin Oligomerization:Effects of Supports and Ni Sites on Activity and Selectivity

A series of Ni/ZSM-5 containing a small amount of Ni was prepared by an ion exchanged method.The impact of the n(SiO_(2))/n(Al_(2)O_(3))ratio on the catalytic activity was studied using the samples 0.09Ni/ZSM-5(60)and 0.09Ni/ZSM-5(130).To determine the interaction between the Ni species and acid sites on the surface of the catalyst,the catalysts were characterized by N2 adsorption-desorption,X-ray diffraction(XRD),scanning electron microscopy(SEM),and UV-vis spectroscopy.The performance of the catalysts for the catalytic oligomerization of 1-hexene was investigated in detail.The nickel species were found to be uniformly distributed in all the catalysts.It was discovered that the oligomerization activity of the catalyst can be improved using Ni species;however,the contribution of Brønsted acids in oligomerization reactions is greater than that of Ni sites and Lewis acids.

Mechanism Study of BF_(3)/n-Butanol-catalyzed 1-Decene Oligomerization Reaction

The active catalysts of the BF_(3)/n-C_(4)H_(9)OH-catalyzed 1-decene oligomerization reaction,as well as the distribution of the reaction products,was investigated by molecular simulation.The calculation results show that(BF_(3))_(2)·n-C_(4)H_(9)OH catalyzes the 1-decene oligomerization reaction with higher activity compared to BF_(3)·n-C_(4)H_(9)OH,which is the most catalytically active substance in the BF_(3)/n-C_(4)H_(9)OH catalyst system.The reaction energy barriers and heats of reaction of chain initiation,chain growth,and chain termination in BF_(3)/n-C_(4)H_(9)OH-catalyzed 1-decene oligomerization are calculated to reveal the product distribution.The calculation results show that the contents of the oligomerization reaction products in descending order are trimer,tetramer,pentamer,and dimer.The calculated results were consistent with the experimentally obtained product distribution.

Human islet amyloid polypeptide oligomers stabilized and probed by MAS NMR

The capture and characterization of oligomers are extremely important in the studies of amyloid aggregation of proteins and peptides.Oligomers are critical intermediates that can impact the structures of amyloid fibrils.Moreover,it is widely accepted that oligomers are the most toxic species along the aggregation pathway[1e4].The studies of oligomers are believed to shed light on the molecular mechanism of amyloid fibrillation and probably the medical clues for related diseases.In vitro investigations of amyloid oligomers are challenging due to their transient and polymorphic nature[5].This is particularly evident in the case of human type-2 diabetes-associated islet amyloid polypeptide(hIAPP),which tends to rapidly form polymorphic fibrils within minutes[6].Notably,hIAPP demonstrates a higher propensity for rapid aggregation compared to other amyloid proteins such as a-synuclein[7].

Oligomeric procyanidins combined with Parabacteroides distasonis ameliorate high-fat diet-induced atherosclerosis by regulating lipid metabolism,inflammation reaction and bile acid metabolism in ApoE^(-/-)mice

Atherosclerosis(AS)is the main pathological basis of cardiovascular diseases.Hence,the prevention and treatment strategies of AS have attracted great research attention.As a potential probiotic,Pararabacteroides distasonis has a positive regulatory effect on lipid metabolism and bile acids(BAs)profile.Oligomeric procyanidins have been confirmed to be conducive to the prevention and treatment of AS,whose antiatherosclerotic effect may be associated with the promotion of gut probiotics.However,it remains unclear whether and how oligomeric procyanidins and P.distasonis combined(PPC)treatment can effectively alleviate high-fat diet(HFD)-induced AS.In this study,PPC treatment was found to significantly decrease atherosclerotic lesion,as well as alleviate the lipid metabolism disorder,inflammation and oxidative stress injury in ApoE^(-/-)mice.Surprisingly,targeted metabolomics demonstrated that PPC intervention altered the BA profile in mice by regulating the ratio of secondary BAs to primary BAs,and increased fecal BAs excretion.Further,quantitative polymerase chain reaction(qPCR)analysis showed that PPC intervention facilitated reverse cholesterol transport by upregulating Srb1 expression;In addition,PPC intervention promoted BA synthesis from cholesterol in liver by upregulating Cyp7a1 expression via suppression of the farnesoid X receptor(FXR)pathway,thus exhibiting a significant serum cholesterol-lowering effect.In summary,PPC attenuated HFD-induced AS in ApoE^(-/-)mice,which provides new insights into the design of novel and efficient anti-atherosclerotic strategies to prevent AS based on probiotics and prebiotics.

Effect of acid density of HZSM-5 on the oligomerization of ethylene in FCC dry gas

The oligomerization of ethylene in FCC dry gas over HZSM-5 catalyst with different Si/A12 ratios was studied. The effect of acid density of catalyst on the oligomerization of ethylene was discussed. By increasing the acid density of catalyst, ethylene conversion showed a linear increase, while the yields of olefins decreased when the acid density of catalyst exceeded 0.14mmolNH3/g owing to a promotion of hydrogen transfer reaction. Through comparing the average distance between acid sites on catalyst with kinetic diameters of olefins, it was found that the dimerization of ethylene was not restrained by the sparse distribution of acid sites, while the hydrogen transfer reaction of C3 and C4 olefins was limited. On these bases, a conclusion is proposed that the dimerization of ethylene proceeded via Eley-Rideal mechanism, while the hydrogen transfer reaction of C3 and C4 olefins followed the Langmuir-Hinshelwood mechanism.

Nucleotide-binding oligomerization domain 1 and Helicobacter pylori infection: A review

Nucleotide-binding oligomerization domain 1(NOD1) is an intracellular innate immune sensor for small molecules derived from bacterial cell components. NOD1 activation by its ligands leads to robust production of pro-inflammatory cytokines and chemokines by innate immune cells, thereby mediating mucosal host defense systems against microbes. Chronic gastric infection due to Helicobacter pylori(H. pylori) causes various upper gastrointestinal diseases, including atrophic gastritis, peptic ulcers, and gastric cancer. It is now generally accepted that detection of H. pylori by NOD1 expressed in gastric epithelial cells plays an indispensable role in mucosal host defense systems against this organism. Recent studies have revealed the molecular mechanism by which NOD1 activation caused by H. pylori infection is involved in the development of chronic gastritis and gastric cancer. In this review, we have discussed and summarized how sensing of H. pylori by NOD1 mediates the prevention of chronic gastritis and gastric cancer.

Oligomerization and Polymerization of Ethylene Initiated by a Novel Ni(Ⅱ)-Based Acetyliminopyridine Complexes as Single-Site Catalysts

Novel Ni（II）-based acetyliminopyridine complexes 1b, 2b, 3b （1-3b）, which are synthesized from ligands 1a, 2a, 3a （1-3a） and [NiCl2（DME）], are suitable precursors for the catalysts that are necessary for ethylene oligomerization and polymerization reactions, activated by methylaluminoxane （MAO）. The MAO-treated 1-3b presents an active catalytic center, which may oligomerize and polymerize ethylene to produce linear α-olefins and polyethylene, respectively. The molecular weight distributions of oligomers that are obtained are in good agreement with the Schulz-Flory rules for oligomers〉C4. The activity of 3b-MAO complex is 6.3×10^7 g/（molNi.h） at 50 ℃. The activities and molecular weight distributions of oligomers show significant reliance on the structures of catalyst precursors.

Nucleotide oligomerization domain 2 contributes to the innate immune response in THCE cells stimulated by Aspergillus fumigatus conidia

AIM: To investigate the expression of nucleotide oligomerization domain 2 (NOD2) in the immortalized human corneal epithelial cell line (THCE), and its role in the innate immune response triggered by inactive Aspergillus fumigatus (Af) conidia. METHODS: The normal THCE cells were investigated as controls. After incubation with inactive Af conidia for 0.5, 2, 4, 6, and 8 hours, THCE cells were harvested, mRNA expression of NOD2 and receptor interacting protein 2 (RIP2) was detected by RT-PCR. Intracellular proteins including NOD2, NF-kappa B and proinflammatory cytokines such as TNF-alpha, IL-8, IL-6 in the cell supernatant were analyzed by ELISA. RESULTS: Our data indicate that NOD2 expressed in the normal THCE cells. After triggered by the inactive Af conidia, the expression of NOD2, RIP2 mRNA and the secretion of NOD2, NF-kappa B, TNF-alpha, IL-8, IL-6 both increased in a time-depended manner, and reached the peak point at 4, 6, 6, 4, 6, 6, 4 hours, respectively. And after pretreated with NOD2 neutralizing antibody, the expression of RIP2, NF-kappa B, TNF-alpha, IL-8 both decreased dramatically at the peak point, while the secretion of IL-6 changed little. CONCLUSION: The results of this study suggest that NOD2 exists and expresses in the THCE cells, and contributes to the innate immune responses triggered by inactive Afconidia by induction of proinflammatory cytokines such as TNF-alpha and IL-8 through the NF-kappa B pathway.

The Solvent Effect on the Chemoselectivity of Palladium-catalyzed Oligomerization of 3,3-Dimethyl-1-butyne

The chemoselectivities of PdCl2 and CuCl2-catalyzed oligomerization of 3, 3-dimethyl-butyne: 1, 3, 5-tri-tert-butylbenzene, 2, 2, 7, 7-tetramethyl-3, 6-dichloro-3, 5-octadiene and 2, 2, 7, 7- tetramethyl-3, 5-octadiyne were obtained, respectively, by regulating the polarity of the solvent.

Dealuminated ZSM-5 Zeolite Catalyst for Ethylene Oligomerization to Liquid Fuels

Ethylene oligomerization using ZSM-5 zeolite was investigated to study the role of Bronsted acid sites in the formation of higher hydrocarbons. The oligomerization of olefins, dependent on the acidity of ZSM-5 zeolite, is an important step in the conversion of natural gas to liquid fuels. The framework Si/Al ratio reflects the number of potential acid sites and the acid strength of the ZSM-5 catalyst. ZSM-5 with the mole ratio SiO2/Al2O3 equal to 30 was dealuminated for different periods of time according to the acidic ion-exchange method to produce ZSM-5 with various Si/Al ratios. The FT-IR analysis revealed that the integrated framework aluminum band, non-framework aluminum band, and silanol groups areas of the ZSM-5 zeolites decreased after being dealuminated. The performance of the dealuminated zeolite was tested for ethylene oligomerization. The results demonstrated that the dealumination of ZSM-5 led to higher ethylene conversion, but the gasoline selectivity was reduced compared to the performance of a ZSM-5 zeolite. The characterization results revealed the amount of aluminum in the zeolitic framework, the crystallinity of the ZSM-5 zeolite, and the Si/Al ratio affected the formation of Bronsted acid sites. The number of the Bronsted acid sites on the catalyst active sites is important in the olefin conversion to liquid hydrocarbons.

Synergetic Effect of Y Zeolite and ZSM-5 Zeolite Ratios on Cracking, Oligomerization and Hydrogen Transfer Reactions

The objective of this study is to explore the optimum composition of Y and ZSM-5 zeolites to develop novel catalysts for obtaining lower gasoline olefins content and higher propylene yield. Five composite zeolite catalysts with varying Y zeolite/ZSM-5 zeolite ratios have been prepared in this work to investigate the synergy between the Y zeolite and ZSM-5 zeolite on the selectivity to protolytic cracking, β-scission, oligomerization, and hydrogen transfer reactions using a FCC naphtha feedstock at 480 ℃ in a confined fluidized bed reactor. Experimental results showed that the composite catalyst with a Y zeolite/ZSM-5 zeolite ratio of 1:4 had the highest protolytic cracking and β-scission ability, which was even higher than that of pure ZSM-5 catalyst. On the other hand, the catalyst with a Y zeolite/ZSM-5 zeolite ratio of 3:2 exhibited the strongest hydrogen transfer functionality while the pure Y zeolite based catalyst had the highest oligomerization ability. For all the catalysts tested, increasing conversion enhanced the selectivity to protolytic cracking and hydrogen transfer reactions but reduced the selectivity to β-scission reaction. However, no clear trend was identified for the selectivity to oligomerization when an increased conversion was experienced.

Ethylene Oligomerization Promoted by Nickel Complexeswith 8-Iminoquinoline Derivatives

A series of 8-iminoquinoline derivatives nickel complexes were synthesized to proceed high activity in ethylene oligomerization.

Nickel Complexes Bearing Bidentate SchifF Base as Ethylene Oligomerization Catalysts

Several nickel complexes [N,N]NiBr_2, in which [N,N] indicates bidentatenitrogen-containing ligands (1: [N,N]=N-(2,6-diisopropylphenyl)pyridine-2-carboxaldimine(C_(18)H_(22)N_2); 2: N-(2,6-diisopropylphenyl)-6-methylpyridine-2-carboxaldimine (C_(19)H_(24)N_2);3: N-(2,4,6-trimethylphenyl)pyridine-2-carboxaldimine(C_(15)H_(16)N_2); 4:N-(2,4,6-trimethylphenyl)-6-methylpyridine-2-carboxaldimine (C_(16)H_(18)-N_2) were synthesized.Some of the nickel complexes exhibit high activity for ethylene oligomerizatiori in the presence ofan organoaluminum activator. The main factor affecting the activity and the structure of oligomersis the steric effect of substituents on [N,N] ligands. Methylaluminoxane (MAO) -activated catalystsshowed higher activities and produced oligomers with higher molecular weight than Et_2AlCl-activatedones. The oligomerization in toluene rather than hexane results in much higher activity, and theoligomers produced in toluene have relatively high molecular weight. With activation of MAO orEt_2AlCl, the [N,N]NiBr_2 system tended to produce highly branched oligomers with low α-olefincontent, but the α-olefin content could be increased by changing the reaction conditions.

Olefin oligomerization via new and efficient Bronsted acidic ionic liquid catalyst systems

Olefin oligomerization reaction catalyzed by new catalyst systems（a Br？nsted‐acidic ionic liquid as the main catalyst and tricaprylylmethylammonium chloride as the co‐catalyst） has been investigat‐ed. The synthesized Br？nsted acidic ionic liquids were characterized by Fourier transform infrared spectroscopy（FT‐IR）, ultraviolet‐visible spectroscopy（UV）, ^1H nuclear magnetic resonance（NMR）, and ^13 C NMR to analyze their structures and acidities. The influence of different ionic liquids, ionic liquid loading, different co‐catalysts, catalyst ratios（mole ratio of ionic liquid to co‐catalyst）, reac‐tion time, pressure, temperature, solvent, source of reactants, and the recycling of catalyst systems was studied. Among the synthesized ionic liquids, 1‐（4‐sulfonic acid）butyl‐3‐hexylimidazolium hydrogen sulfate（[HIMBs]HSO4） exhibited the best catalytic activity under the tested reaction con‐ditions. The conversion of isobutene and selectivity of trimers were 83.21% and 35.80%, respec‐tively, at the optimum reaction conditions. Furthermore, the catalyst system can be easily separated and reused; a feasible reaction mechanism is proposed on the basis of the distribution of experi‐mental products.

Influence of a nucleotide oligomerization domain 1 (NOD1) polymorphism and NOD2 mutant alleles on Crohn's disease phenotype

AIM： To examine genetic variation of nucleotide oligomerization domain 1 （NOD/） and NOD2, their respective influences on Crohn＇s disease phenotype and gene-gene interactions. METHODS： （ND1＋32656＊1） NOD1 polymorphism and SNPS, SNP12 and SNP13 of NOD2 were analyzed in 97 patients and 50 controls. NOD2 variants were determined by reaction restriction fragment length polymorphism analysis. NOD1 genotyping and NOD2 variant confirmation were performed by specific amplification and sequencing. RESULTS： The distribution of NOD1 polymorphism in patients was different from controls （P = 0.045） and not altered by existence of NOD2 mutations. In this cohort, 30.92% patients and 6% controls carried at least one NOD2 variant （P 〈 0.001） with R702W being the most frequent variant. Presence of at least one NOD2 mutation was inversely associated with colon involvement （9.09% with colon vs 36.4% with ileal or ileocolonic involvement, P = 0.04） and indicative of risk of penetrating disease （52.63% with penetrating vs 25.64% with non-penetrating or stricturing behavior, P = 0.02）. L1007finsC and double NOD2 mutation conferred the highest risk for severity of disease （26.3% with penetrating disease vs 3.8% with non-penetrating or stricturing behavior presented L1007finsC, P = 0.01 and 21.0% with penetrating disease vs 2.5% with non-penentrating or stricturing behavior carried double NOD2 mutation, P = 0.007）. Exclusion of patients with NOD2 mutations from phenotype/NODl-genotype analysis revealed higher prevalence of ＊1＊1 genotype in groups of younger age at onset and colonic location.CONCLUSION： This study suggests population differences in the inheritance of risk NOD1 polymorphism and NOD2 mutations. Although no interaction between NOD1-NOD2 was noticed, a relationship between disease location and Nod-like receptor molecules was established.

Mitotic phosphorylation of PRC1 at Thr470 is required for PRC1 oligomerization and proper central spindle organization

During cell division, chromosome segregation is orchestrated by the interaction of spindle microtubules with the centromere. A dramatic remodeling of interpolar microtubules into an organized central spindle between the separating chromatids is required for the initiation and execution ofcytokinesis. Central spindle organization requires mitotic kinesins, the chromosomal passenger protein complex, and microtubule bundling protein PRC 1. PRC 1 is phosphorylated by Cdc2 at Thr470 and Thr481 during mitosis. However, the functional relevance of PRC 1 phosphorylation at Thr470 has remained elusive. Here we show that expression of the non-phosphorylatable mutant PRC 1T470A but not the phospho-mimicking mutant PRC 1^T470E causes aberrant organization of the central spindle. Immunoprecipitation experiment indicates that both PRC 1^T470A and PRC 1^T470E mutant proteins associate with wild-type PRC 1, suggesting that phosphorylation of Thr470 does not alter PRC 1 self-association. In addition, in vitro co-sedimentation experiment showed that PRC 1 binds to microtubule independent of the phosphorylation state of Thr470. Gel-filtration experiment suggested that phosphorylation of Thr470 promotes oligomerization of PRC 1. Given the fact that prevention of the Thr470 phosphorylation inhibits PRC 1 oligomerization in vitro and causes an aberrant organization of central spindle in vivo, we propose that this phosphorylation-dependent PRC 1 oligomerization ensures that central spindle assembly occurs at the appropriate time in the cell cycle.

Oligomerization of 1-Decene: Catalyzation by Immobilized AlCl_3/γ-Al_2O_3 Catalyst in Fixed-bed Reactor

1-Decene was oligomerized over the supported AlCl3/γ-Al2O3 catalyst in a fixed-bed reactor. The effects of temperature and LHSV on oligomerization of 1-decene were investigated and the synthetic PAO was characterized with GC technique. Furthermore, the life of immobilized catalyst was tested and the mechanism of catalyst deactivation was discussed. The results showed that with an increasing temperature, the PAO yield increased and the kinematic viscosity of oil decreased. The GC results indicated that the synthesized PAO was a mixture consisting of dimers, trimers, tetramers and pentamers. The results of chloride content measurements and BET tests showed that catalyst deactivation could be mainly attributed to the loss of active components.

Identification of the structure of Ni active sites for ethylene oligomerization on an amorphous silica-alumina supported nickel catalyst

The structure of Ni active sites supported on amorphous silica-alumina supports with different contents of Al_(2)O_(3)loadings in relation to their activities in ethylene oligomerization were investigated.Two kinds of Ni sites were detected by in situ FTIR-CO and H_(2)-TPR experiments,that are Ni^(2+)cations as grafted on weak acidic silanols and Ni^(2+)cations at ion-exchange positions.The ethylene oligomerization activities of these Ni/ASA catalysts were found an ascending tendency as the Al_(2)O_(3)loading decreased,which could be attributed to the enriched concentration of Ni^(2+)species on acidic silanols with a weaker interaction with the amorphous silica-alumina support.These Ni^(2+)species were more easily to be evolved into Ni^(+)species,which has been identified to be the active sites of ethylene oligomerization.Thus,it seems reasonable to conclude that Ni^(2+)species grafted on acidic silanols were the precursors of active sites.

Nucleotide-binding Oligomerization Domain-1 Ligand Induces Inflammation and Attenuates Glucose Uptake in Human Adipocytes

Objective To investigate the effects of stimulant for nucleotide-binding oligomerization domain 1 （NOD1） on secretion of proinflammatory chemokine/cytokines and insulin-dependent glucose uptake in human differentiated adipocytes. Methods Adipose tissues were obtained from patients undergoing liposuction. Stromal vascular cells were extracted and differentiated into adipocytes. A specific ligand for NOD1, was administered to human adipocytes in culture. Nuclear factor-κB transcriptional activity and proinflammatory chemokine/cytokines production were determined by reporter plasmid assay and enzyme-linked immunosorbent assay, respectively. Insulin-stimulated glucose uptake was measured by 2-deoxy-D-[ 3 H] glucose uptake assay. Furthermore, chemokine/cytokine secretion and glucose uptake in adipocytes transfected with small interfering RNA （siRNA） targeting NOD1 upon stimulation of NOD1 ligand were analyzed. Results Nuclear factor-κB transcriptional activity and monocyte chemoattractant protein-1 （MCP-1）, interleukin （IL）-6, and IL-8 secretion in human adipocytes were markedly increased stimulated with NOD1 ligand （all P〈0.01）. Insulin-induced glucose uptake was decreased upon the activation of NOD1 （P〈0.05）. NOD1 gene silencing by siRNA reduced NOD1 ligand-induced MCP-1, IL-6, and IL-8 release and increased insulin-induced glucose uptake （all P〈0.05）. Conclusion NOD1 activation in adipocytes might be implicated in the onset of insulin resistance.

T-49 Catalyst of High Nonene Selectivity for Oligomerization of Propylene

Ｔ４９ＣａｔａｌｙｓｔｏｆＨｉｇｈＮｏｎｅｎｅＳｅｌｅｃｔｉｖｉｔｙｆｏｒＯｌｉｇｏｍｅｒｉｚａｔｉｏｎｏｆＰｒｏｐｙｌｅｎｅＨｕａｎｇＥｒｆｅｎｇ，ＣｈｅｎＹｏｎｇｆｕ，ＺｈｕＺｈｉｒｏｎｇ（ＳｈａｎｇｈａｉＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅｏｆ...