Bitcoin Forum

i would like to ask what is the highest transaction per second in blockchain? is it possible for a blockchain having 100millin transaction per second?

Yes it is possible but it will take time, so far the highest is Ternio.
Ternio has built Lexicon — the highest scaling blockchain solution currently available. Lexicon is capable of delivering more than 1.2 million transactions per second (TPS), fully decentralized and on-chain.

But as of last year ending..  The list
First

Ripple built their own Payment Channel specifically designed for XRP, the digital asset native to RCL. An XRP Payment Channel allows transaction throughput to increase to tens of thousands of transactions per second, bringing our scalability to the same level as Visa.

Second

The Steem platform is built upon Graphene, the same technology that powers BitShares, another blockchain network created by Dan Larimer, also a co-founder of Steem and Steemit with Ned Scott. This technology has been demonstrated sustaining over 1,000 transactions per second on a distributed test network and can easily scale to 10,000 or more.

Third

NEM/XEM An application was written to sequence the transactions in a series of constant stream of transactions from each of the 10.8 million accounts. The results obtained were very encouraging. The average transaction rate came to 3,085.77 tps completing the experiment in just under an hour. It hit a peak of 4,142 tps.

Fourth

Stratis will have an official visual block explorer and API that should be able to support up to 20,000 requests per second.

Fifth

Monero already has a dynamic block size. Theoretically, nodes could, if the bandwith allowed it, handle over 1000 transactions per second with modern hardware.

Sixth

Litecoin has a maximum capacity of 56 tx/second. Lightning would increase this speed significantly.

Seventh

Dash has a current limitation of 28 tx/second. A change to 2MB block size limitation, would allow up to 56 tx/second.

Eighth

Ethereum is fundamentally limited by single threaded performance of a CPU. Discussion over GAS costs/etc is misleading because the maximum GAS that an individual node can process is limited and there is relatively little room to optimize execution.Early test networks reached 25 tx/second. With optimizations they may be able to reach 50 tx/second. Ethereum scalability improvements (PoS and Sharding) up to 30,000 tc/second.

Ninth

Ethereum Classic has a maximum capacity of 14 tx/second per second.

Tenth

Bitcoin is limited to 3 tx/second by an artificial block size which could be increased to 100 tx/second without running into the CPU limit. 10 minute block times. Bitcoin scalability improvements (Segwit and Lightening network) up to 50,000 tx/second.

- list by cyberblock.

There is no real limit with Lightning network. You can have as many transactions as you want with LN, it just depends on when you find it useful to use it.

Considering each full node (necessary) would not be able to download even a small percentage of that, I believe it is not possible.

A blockchain by itself could maybe handle that volume - but not a decentralized one - not with our current technology.

I assume you meant distributed not a decentralized one.
You can still have a blockchain that could be considered decentralized even though it is not distributed to every node equally.

It is a debatable issue. Hopefully advancements in hardware would make second layer scaling solutions unnecessary.