Dehydration with a microporous adsorbent of natural gas used as motor fuel. Experimental and modeling study of the adsorption and desorption phases.

An experimental and theoretical study of the dehydration of natural gas using microporous silica beds for motor fuel technology in extreme winter climates is described. Analytical solutions to the problem of non-isothermal adsorption and desorption are based on Heaviside’s operational method and Laplace integral transformation. Experimental and modeling distributions of moisture and temperatures of gas at the inlet and outlet of the silica beds for each adsorption - desorption phase at different times are presented. The distribution of moisture within the beds for the full dehydration - regeneration cycle is determined

The Competitive Diffusion of Gases in a Nanoporous Zeolite Using a Slice Selection Procedure

The study of the co-diffusion of several gases through a microporous solid and of the resulting instantaneous distribution (out of equilibrium) of the adsorbed phases is particularly important in many fields, such as gas separation, heterogeneous catalysis, etc. Classical H NMR imaging is a good technique for visualizing these processes but, since the signal obtained is not specific for each gas, each experiment has to be performed several times under identical conditions, and each time with only one incompletely deuterated gas. In contrast, we have proposed a new NMR imaging technique (based on the so-called NMR slice selection procedure) which gives a signal characteristic of each adsorbed gas. It can therefore provide directly, at every moment and at every level of the crystallite bed, the distribution of several gases competing in diffusion and adsorption. Solutions to the direct and inverse problems are based on Heaviside’s operational method and Laplace integral transformation. New procedures for identifying diffusion coefficients for co- diffusing components (benzene and hexane) in intra- and intercrystallite spaces were implemented, using high-speed gradient methods and mathematical diffusion models, as well as the NMR spectra of the adsorbed mass distribution of each component in the zeolite bed. These diffusion coefficients were obtained as a function of time for different positions along the bed. Benzene and hexane concentrations in the inter- and intracrystallite spaces were calculated for every position in the bed and for different adsorption times

Enhancement of the Hydrogen Sorption on Mesoporous Carbon by Doping with Palladium Nanoparticles

We have used the matrix synthesis protocol of Ryoo et al. for the preparation of highly ordered cubic mesoporous carbon (CMK-1) using mesoporous silica (MCM-48) as a template, in order to prepare palladium-doped CMK-1. The carbon obtained has a high surface area of 1800 m2g-1, a large porous volume of 1.14 cm3g-1 and average pore diameter of 3.03 nm. Step-by-step formation of mesoporous carbon was followed by X-ray diffraction, FTIR, N2 adsorption desorption and TPD mass-spectrometry. The physical data of CMK-1 are hardly changed by Pd incorporation (CMK-1/Pd). Transmission electron microscopy and Raman spectroscopy show that the framework of the highly ordered mesoporous carbon/Pd consists of an aligned carbon phase with a graphite mode region. The potential application of CMK-1 and CMK-1/Pd as sorbents for hydrogen storage is discussed.Мезопористий вуглець, допований паладієм, був одержаний шляхом матричного синтезу з використанням мезопористого кремнезему як темплату. Отримані зразки високовпорядкованого кубічного мезопористого вуглецю характеризуються питомою площею поверхні до 1800 м2/г, великим об’ємом пор до 1,14 cм3/г і середнім діаметром від 3,03 нм. Стадії одержання мезопористого вуглецю та композитного матеріалу контролювали методами рентгенівської дифракції, ІЧ-спектроскопії з Фур'є-перетворенням, низькотемпературної адсорбції азоту та ТПД мас-спектрометрії. Встановлено, що допування зразків паладієм не приводить до руйнування структури матриці; згідно з даними просвічуючої електронної мікроскопії та спектроскопії комбінаційного розсіювання структура високовпорядкованого мезопористого композиту складається з впорядкованої вуглецевої фази з ділянками графіту і наночастинок паладію, інкорпорованого в мезопорах матриці, а композитні зразки показують підвищену сорбційну ємність по водню.Мезопористий углерод, допированный палладием, был получен методом матричного синтеза с применением в качестве темплата мезопористого кремнезема. Получены образцы высокоупорядоченного кубического мезопористого угля, которые характеризуются большой удельной площадью поверхности 1800 м2/г, большим объемом пор до 1,14 cм3/г и средним диаметром от 3,03 нм. Стадии получения мезопористого угля и композитного материала контролировали методами рентгеновской дифракции, ИК-спектроскопии с Фурье-преобразованием, низкотемпературной адсорбции азота и ТПД масс-спектрометрии. Установлено, что допирование образцов палладием не приводит к разрушению структуры матрицы; согласно данным просвечивающей электронной микроскопии и спектроскопии комбинационного рассеивания структура высокоупорядоченного мезопористого композита состоит из упорядоченной углеродной фазы с участками графита и наночастиц палладия, инкорпорированного в мезопорах матрицы, а полученные композитные образцы показывают повышенную сорбционную емкость по водороду

Molecular hydrogen and catalytic combustion in the production of hyperpolarized 83Kr and 129Xe MRI contrast agents

Hyperpolarized (hp) 83Kr is a promising MRI contrast agent for the diagnosis of pulmonary diseases affecting the surface of the respiratory zone. However, the distinct physical properties of 83Kr that enable unique MRI contrast also complicate the production of hp 83Kr. This work presents a radically new approach in the generation of hp 83Kr that can likewise be utilized for the production of hp 129Xe. Molecular nitrogen, typically used as buffer gas in spin exchange optical pumping (SEOP), was replaced by molecular hydrogen without penalty for the achievable hyperpolarization. In this particular study, the highest obtained nuclear spin polarizations were P = 29 % for 83Kr and P = 63 % for 129Xe. The results were reproduced over many SEOP cycles despite the laser induced on-resonance formation of rubidium hydride (RbH). Following SEOP, the H2 was reactively removed via catalytic combustion without measurable losses in hyperpolarized spin state of either 83Kr or 129Xe. Highly spin polarized 83Kr can now be purified for the first time to provide high signal intensity for the advancement of in vivo hp 83Kr MRI. More generally, a chemical reaction appears as a viable alternative to the cryogenic separation process, the primary purification method of hp 129Xe for the past 2 . decades. The inherent simplicity of the combustion process will facilitate hp 129Xe production and should allow for on-demand continuous flow of purified and highly spin polarized 129Xe

The STAR-RICH Detector

The STAR-RICH detector extends the particle idenfication capabilities of the STAR spectrometer for charged hadrons at mid-rapidity. It allows identification of pions and kaons up to ~3 GeV/c and protons up to ~5 GeV/c. The characteristics and performance of the device in the inaugural RHIC run are described