Gasoline Production Fischer-Tropsch Synthesis using Bi-Functional Structured Catalytic Reactors

Gasoline accounts for more than half of U.S. transportation energy usage and its consumption continues growing. Crude oil is where gasoline originates from. However, crude oil reserves are limited in most of the countries around the world. U.S. imports thousand barrels of gasoline per day, making it highly dependent on foreign oil import which imposes a threat to U.S. homeland security. To make the U.S. gasoline independent, alternative processes such as Fischer-Tropsch Synthesis process (FTS) can be promising to mitigate high gasoline demand on transportation fuel and increase fuel diversity. However, scalable, selective, and more efficient FTS technologies are required to align with the need for high gasoline production. Energy independence and security are some of the merits of making FTS a more efficient and less centralized process. Among the many challenges in FTS catalysis, selectivity to gasoline-range products is vital to be addressed. FTS uses synthesis gas (syngas, CO and H2) as feedstock. Normally, it follows the Anderson-Schulz-Flory (ASF) distribution. FTS can be environmentally benign and friendly, since there is no sulfur or nitrogen in the products. While FTS is conceived as a diesel-producing process, using either a cobalt or an iron catalyst. A bifunctional catalyst can be formulated and applied to improve gasoline selectivity via oligomerization, aromatization, and isomerization reactions. This thesis aims at exploring the potential of structured catalysts as candidates for intensified FTS process selective to gasoline production. In this thesis, structured bifunctional catalysts consisting of a monolith support, cobalt catalyst, and ZSM-5 with micro- or mesoporosity were synthesized and tested in a fixed bed reactor. Fine-tuning of the catalyst and process condition led to desirable gasoline selectivity. However, the CO conversion was hindered due to the mass transfer limitations in the microporous zeolite. Mesopores were, thus, introduced later to relax mass transfer limitation. CO conversion increased to near 90%, while maintaining high gasoline selectivity with the introduction of the mesopores. A highly active and selective structured catalyst was formulated. After successful synthesis and testing of the bifunctional structured catalysts, modeling was performed to assess the techno-economic feasibility and potential of the new catalytic process. The experimental data was used in a modular Gas-to-Liquid (GTL) plant to further study the potential of the structured catalysts for an intensified process, aiming to monetize stranded natural gas

Exploring Users’ Interactive Behaviors in Online Group: A Case Study of QQ Group “TuanRenTang”

The users’ interactive behaviors of the online group chat and an accurate identification of users’ interaction, which can provide method support for mining user interests and the crowd labeling, was analyzed in this paper. By using social network analysis method, the study took QQ Group “TuanRenTang” as an example to analyze users’ interactive behaviors, discover users’ interaction relationships, construct interaction networks, and explore the interaction types and community detection. The findings suggested that both explicit and implicit interaction exist in the same topic discussion. Users could be classified into four categories: active interaction, general interaction, passive interaction and lurking interaction based on different user activity. Besides, twenty “experts” and eight communities on the basis of interaction networks had been found out from the sample data of “TuanRenTang” chat records

Platform Performance Based On The Network Externality

An increasing number of markets today are organized around platforms that enable consumers to access and/or purchase various goods and services. Considering the presence of network externality, we study the precondition in which whether the buyer will join the platform. Moreover, this paper investigates the performances of platform in the supply chain in which the leadership belongs to the retailor. We find the optimal decision-making strategies, and the sellers will join the online platform when the network externality is large enough. In addition, the retailer’s optimal profit and demand on offline platform will increase with the rising of network externality, whereas their demand on online platform will decrease, and the manufacturer’s optimal profit and demand on online platform will increase

An Efficient ID-based Proxy Signature Scheme from Pairings

This paper proposes a new ID-based proxy signature scheme based on the bilinear pairings. The number of paring operation involved in the verification procedure of our scheme is only one, so our scheme is more efficient comparatively. The new scheme can be proved secure with the hardness assumption of the k-Bilinear Diffie-Hellman Inverse problem, in the random oracle model

Quantifying evolution of soot mixing state from transboundary transport of biomass burning emissions

Incomplete combustion of fossil fuels and biomass burning emit large amounts of soot particles into the troposphere. The condensation process is considered to influence the size (Dp) and mixing state of soot particles, which affects their solar absorption efficiency and lifetimes. However, quantifying aging evolution of soot remains hampered in the real world because of complicated sources and observation technologies. In the Himalayas, we isolated soot sourced from transboundary transport of biomass burning and revealed soot aging mechanisms through microscopic observations. Most of coated soot particles stabilized one soot core under Dp &lt; 400 nm, but 34.8% of them contained multi-soot cores (nsoot ≥ 2) and nsoot increased 3–9 times with increasing Dp. We established the soot mixing models to quantify transformation from condensation- to coagulation-dominant regime at Dp ≈ 400 nm. Studies provide essential references for adopting mixing rules and quantifying the optical absorption of soot in atmospheric models.</p