Three chemistry-based start-ups have raised funds from investors. Siluria Technologies, which is developing what it calls the first commercially viable process to directly convert methane to ethylene, raised $25 million in a financing round led by Saudi Arabia’s National Petrochemical Industrial Co. Siluria says it has raised some $150 million since its founding in 2008. Rive Technology, a Princeton, N.J.-based catalyst and separations start-up, raised $17 million from investors including Saudi Aramco Energy Ventures and Zeolyst International. Rive will use the funds to further commercialize its zeolite technology for fuel refining and petrochemical manufacturing. And Anellotech, developer of a thermal catalytic biomass route to aromatics such as benzene and p-xylene, raised $7 million from what it calls a new, strategic investor. Anellotech says the money is the first tranche of a planned $10 million fund-raising round.